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Open Rear End in 69 with HD Package

redfishtony

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Apr 17, 2008
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Thomasville GA
My 69 with the HD options has an open rear end. Can anyone tell me if this is correct or should it at least have the limited slip diff in it. Seams like they would not have put the opens in the trucks that where HD. Also can I replace the diff with any ford 9", ie F150, Full size Bronco etc.. or are they different in the early broncos. I know they were produced in the 28 and 35 spline axels. Thanks, TW
 

Pa PITT

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... I want to hear the answer on this question .
My 68 glove box door says it's a 4:57 but open .. I just can't believe it'd be open either.
 

okie4570

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I'm not sure why HD would necessarily mean LS would be standard. All early bronco 9" were 28 spline. The 66' I sold last year was 4.57 and open as well.
 

Nothing Special

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Nov 25, 2016
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Back in the day there were very few option packages, and the packages there were usually had pretty short lists of what came with them. You could usually pick whatever selection of options you wanted. So unless it was shown to be different I'd assume that limited slip would be a different check box than heavy duty.
 

Broncobowsher

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And you are making a huge assumption that nothing has ever been changed at any time in the past 50 years. These things get a lot of modifications, and sometimes questionable repairs. Some by the home mechanic that doesn't know better, other times someone pays a mechanic that doesn't know any better. And there are times where it is just a quick fix with parts on hand, or different parts that someone has that they think might make it better. So you really don't know what you have unless you check, the numbers on the tag simply tell you what it was built with, not what it has now.

A Bronco axle is specific to a Bronco and nothing else. F150 axles have been swapped, generally called a full width or full size axle swap. Makes the Bronco tires stick out past the body as the axles are about 6" wider then a Bronco axle.

And they were all built, in all years, with a 28 spline axles in the back. Regular, heavy duty, or a medium bearing rear axle they are all 28 spline. Unless someone has done an upgrade sometime in the past. Back to that not knowing what has been done between when it was new and when you have it now. 31 Spline was used by Ford in some of the 9" rear axles, just not the early Bronco ones.

The heavy duty has nothing to do with the differential itself. It is a higher GVW package, an extra leaf in the rear springs, a bigger bearing on the axle to handle the extra GVW on the axle, and drum brakes an inch larger in diameter. That is what you got with a heavy duty axle back in '69. And the placard lists a higher GVW, which in some states moves you up a tax bracket. The ride is worse when not loaded as well.
 

DirtDonk

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And if this is what you were wondering, all the 9" center sections will swap out to all 9" housings. Some will have 28 spline side gears and some will have 31 spline diffs, depending on what you source them out of. But other than axle shaft compatibility, the chunk/hogshead/center section/third member/whateveryoucallit will bolt right in to the housing.
As far as I know anyway...

Paul
 

SteveL

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Factory 9" differentials were 28 or 31 spline. Pretty sure the 35 spline is aftermarket. Most of the truck diffs I've pulled at the boneyard were 31's but someone may have more specifics on years and options. If you do find another 28 spline diff it should swap out for yours.
 

charlie6976

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In your search for a nine inch, don't forget old big Ford/Merc/Lincoln cars. Some had LS or some type of locker. Just make sure the spline count (28 or31).



From a little research, the ratios may be to high.:( However, keep an eye out for late 60's/early 70,s performance cars (Merc Cyclone, Fairlane GT, Mustangs). You'll find better gear ratios in these cars. Just an option.
 
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redfishtony

redfishtony

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Thomasville GA
Thanks all. In my post the 35 was a typo, I meant 31. I was asking about the diff not the axels. Sort if I was not clear. I think I was just surprised to see an open diff in my truck. It’s a HD Sport package. Just another learning project. Thanks
 

JGbronc

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Mar 30, 2007
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The heavy duty has nothing to do with the differential itself. It is a higher GVW package, an extra leaf in the rear springs, a bigger bearing on the axle to handle the extra GVW on the axle, and drum brakes an inch larger in diameter. That is what you got with a heavy duty axle back in '69. And the placard lists a higher GVW, which in some states moves you up a tax bracket. The ride is worse when not loaded as well.

Exactly. Could easily be the factory diff.
 

elan

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With an open differential in the rear, what you have is a two wheel drive vehicle.

Early Broncos had an option of TL in front and certainly in the rear. Any time I get another Bronco in, I pull the entire rear diff out and take it to the shop for new bearings, seals and a TL. I will never own another old 4x4 with an open diff in rear.
I'm still on the fence about TL in front.

This goes for Scouts, FJ40/43/45 and Jeeps.
 

Broncobowsher

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My last '69 was born 4.11 gears and limited slip both ends. I wheeled it pretty hard for a few years thinking that is what I had. When I opened it up the rear was an open diff, it had been blown up once before and the limited slip was replaced with an open. It wheeled amazingly well for being open. As long as the springs are soft enough that both tires are on the ground and have traction, it will go. The front was a limited slip and the date code on the toothless dana 30 ring gear was 1976, so that was at least the second time that blew up.

While not the best, it is still pretty amazing how well an open diff will still get you places. Just don't expect it to do anything if a wheel is in the air.
 

broncnaz

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May 22, 2003
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The HD package had several versions I dont have the 69 info but usually there were 2 or 3 versions of it, If you had the 4900lb version then limited slip was pretty much required but lower versions it wasnt.

best thing to do is check the VIN tag what is the axle code? if it has a letter and number then it came with limited slip. If number only then open.

The HD package had more to do with spring rate and axle ratings ie bearing and brake size than open or LS. You could order LS in any bronco.
 

bmc69

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When I bought my first '69 back in the mid 90s, I was surprised to find out that it had the the Dana LS in front (D30) and Equalock in rear 9", all from the factory. After a new clutch pack in the rear, both LS worked well and that rear axle is under a more recent EB project, in fact.
 

pipeline010

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Nov 15, 2017
Messages
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The HD package had several versions I dont have the 69 info but usually there were 2 or 3 versions of it, If you had the 4900lb version then limited slip was pretty much required but lower versions it wasnt.

My 69 has the LS in the lighter rear axle. Very nice feature for the white stuff that dropped here this week.
 

SHX669

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And Only as a matter of interest - in mid 1971 the limited slip front axle was a $28 option and the trac lok rear axle was $40.30 .
 

Nothing Special

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With an open differential in the rear, what you have is a two wheel drive vehicle.

Cute and fun to say, but not true. "Two wheel drive" is almost universally used to mean that two wheels are capable of being driven. A vehicle with driveshafts to both axles is capable of driving all 4 tires. It won't always put power to all of them if it has open diffs, but it's still 4WD.

Early Broncos had an option of TL in front and certainly in the rear. Any time I get another Bronco in, I pull the entire rear diff out and take it to the shop for new bearings, seals and a TL. I will never own another old 4x4 with an open diff in rear.
I'm still on the fence about TL in front.

This goes for Scouts, FJ40/43/45 and Jeeps.

I agree that open diffs are not great for fourwheeling. But in my opinion and experience factory-type limited slips (like TracLoc) are a worse choice, and there are many better choices. In my experience factory limited slips don't help much when you need traction and hurt significantly when you need stability.

For "the best of both worlds" it's hard to argue against a selectable locker. The stability of an open diff (which is unquestionably the leader in that category) and the traction of a spool are both available. But they are expensive and you need to turn them on and off (and they don't always turn off when you want). So they still aren't perfect.

As long as both tires get some traction a Truetrac (there are also other brands now that work the same way) will give better traction than a TracLoc. If one tire gets no traction (like if it's in the air) it won't help as much as a TracLoc. But in my experience almost all of the times a TracLoc is better, it still isn't good enough, and you'd be better off with a locker. And both a Truetrac and a TracLoc will spin you out easier than an open diff if you get on the gas too hard. But only the TracLoc will spin you out when you are coasting around a curve.

In my experience, even an automatic locker (like a Detroit, or a "lunchbox" locker) gives better stability than a TracLoc because they won't spin you out when you are coasting. They can be more annoying as they spin the inside tire when starting around a corner, but they are easier to predict and give MUCH better traction than a TracLoc.

I know other people have different opinions on them than I do, and I'm not saying they are wrong. But in my experience I really don't see any situation where a TracLoc is the right choice.
 
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redfishtony

redfishtony

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Thomasville GA
OK Guys one more question. When I get to my local salvage yard are there any tricks that will help me locate LS, TL or Truetrac rear ends. All of the trucks and cars at this yard are elevated off the ground so it will be easy to turn the rear axels to see if both wheels turn. Is this only the case for a locker or should the TL's react the same way? Also which ones typically had the 28 splines.
 
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redfishtony

redfishtony

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Apr 17, 2008
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Thomasville GA
My axle code is 08 so it shows it being a 3300# open. My tag reads:

WB=092, Color = 6, Model U152, Body 9498, Then a C, Axle = 08, Then under the C theres

a 90.

Any Ideas on the 9498 under body and the C with the 90 under it.
 

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DirtDonk

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...Is this only the case for a locker or should the TL's react the same way? Also which ones typically had the 28 splines.

Limited-slip diffs act the same way as long as the clutches are not totally worn out. The good news is that they have to be totally toast to let one wheel spin in the opposite direction when elevated, so likely you'll get a proper reading.
You should then be able to turn one side and have the other turn in the same direction.

I don't know where there might be a database for what assemblies got 28 spline vs 31sp shafts. There were so many GAWR/GVWR ratings for the different vehicle lines that there's a lot to keep track of. Knowing which one is a "light duty" vs "heavy duty" for an LTD and T-bird for instance, or for a full size van, or 2wd vs 4wd truck is tough to keep track of.

A light duty short bed 2wd F100 for example might have 28 spline axles, while a T-bird with 460 V8 (if such a vehicle existed?) might have 31 spline axles.
Maybe someone has a cheat sheet you can download and print out to take with you. Perhaps one of the other sites like Fordification or one of the Mustang sites that has been around for a long time may have that info.

Granted, it would be nice to be able to narrow it down, but since so many could have been changed out over the years (swapped with a lesser version before junking), the only way to know for sure is to pull an axle and count.

Paul
 
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