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Daily driver transmission

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,160
Manual or auto? Lot's of good options for both. What tire size are you running? Gears? Lockers? What engine do you have? Whatever handles the street can pretty much handle most logging roads.
 
OP
OP
T
Joined
Nov 5, 2024
Messages
8
I am a "SUPER NOOB" to all of this. My Bronco is a 1968 sport package. I'm putting in a 300 inline 6 2 inch body lift (maybe 2.5) would like an automatic but, the inline 6 is from a 68 ford f100 (I think) that also has a NP435 manual trans bolt right on it so, I need schooled in it all. Lucky I found Jack Hagey he put a 300 inline 6 in his EB. I heard that the NP435 is great for rock climbing because of the 6.35:1 first gear. i will be towing a vintage trailer that weights around 2700 lb's. just looking for ideas and imput BUT, not about the motor lol.
 

Timmy390

Contributor
Bronco Guru
Joined
Jan 1, 2011
Messages
5,722
Loc.
Conway, AR
IF you are truly putting in a 300 I-6 (my hat is off to you on that and all that in entails) and if you go manual, M5ODR2 all day long and twice on Sundays

Tim
 

phred

Contributor
Bronco Guru
Joined
Aug 25, 2006
Messages
3,542
Loc.
Earth
The 435 is a great transmission, tough, low geared and quiet compared to the late model aluminum cased options, but it doesn’t have an overdrive and in daily use it is nothing more than a 3 speed with an extra low first gear that is rarely used. I’ve had two trucks with that trans and loved it. At 60 mph on 32” tires the 300 will be spinning close to 3000 rpm’s in 4th gear. Using the M5OR2 will allow you to be in the low 2000 rpm’s. I assume you will need an adapter to use that trans with the 300. Good luck on your swap.
 

bmbm

Sr. Member
Joined
Jun 16, 2007
Messages
645
I am a "SUPER NOOB" to all of this. My Bronco is a 1968 sport package. I'm putting in a 300 inline 6 2 inch body lift (maybe 2.5) would like an automatic but, the inline 6 is from a 68 ford f100 (I think) that also has a NP435 manual trans bolt right on it so, I need schooled in it all. Lucky I found Jack Hagey he put a 300 inline 6 in his EB. I heard that the NP435 is great for rock climbing because of the 6.35:1 first gear. i will be towing a vintage trailer that weights around 2700 lb's. just looking for ideas and imput BUT, not about the motor lol.
The 300 is a great choice in my opinion and I have had several in trucks and vans over the years, and in my F150 now. They are tough and have a lot of torque and would have been a nice option from Ford if there had been a bit more room under the hood. As far as I know any auto trans that will attach to a sbf should work like an AODE and others. If your 68 had a six originally you probably have 4:11 gears so you could factor that into your drivetrain plan regarding tire size etc. If the 300 is to be rebuilt there are options to boost the torque and much information can be found on fordsix.com. Look forward to hear more about your project.
 

Apogee

Contributor
Bronco Guru
Joined
Nov 26, 2005
Messages
6,160
The NP435 is a great truck transmission, and I've daily-driven one in my first truck (73 Dodge W100) and second truck (77 F150) many tens if not hundreds of thousands of miles. That said, it shifts slow and for all practical purposes, is a 3-speed transmission with a granny 1st gear as noted previously. First isn't synchronized, nor is reverse, so shifting in and even out of those gears can be a bit difficult, somewhat depending on the condition of the transmission and how quickly you're trying to shift it. Otherwise, all of the standard Ford small block/Windsor type transmission options should be open to you given that the 300 I6 uses the same bellhousing pattern.

Since you said you would prefer an auto, the EB C4 would be a natural choice since it will work with the D20 directly and won't require a bunch of extra work or cost associated with many other auto trans swaps due to the adapters, cross-members, driveshaft interference issues, etc. Otherwise, AOD(E) is another swap that has become less popular over the years versus the 4R70W, which obsoleted the AOD-E and requires the purchase of a controller. If you're looking to drop that kind of money, for a lot more, you could consider one of the modern modular 6R80 or 10R80 transmission options given the relatively low-RPM torque curve of the 300, as both of these transmissions offer much narrower gaps between gears and would allow for lower axle gears and allow the engine to stay in a relatively narrow RPM band.

If you search, there have been some pretty detailed conversations about the modern automatic transmission swap options. Here's one from all the way back in 2017, but there are several newer threads included a the bottom of the post under "Similar Threads".
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
35,509
You state you are a noob at early Broncos. Before you too invested in the 300, just try mocking it in place. Don't forget all the pulleys, fan, radiator, etc. They are called the big block I6 for a reason. While a few have been swapped over the years, not many have been done. They don't fit well. I recall one that was so tight that they ended up with a rear mounted radiator. Now you want enough cooling to also tow a trailer. I think this is a poor choice.

So you want an automatic. How fancy do you want to get? The dirt simple version is a C4. It will bolt to the 300 and you can use a Bronco version for the transfer case. With the 300 you can use any that would work with a V8, so add in 4R70W to gain overdrive and 6R80 if you want all the gears. But they won't package well. The C4 is your best bet for packaging, and worst choice for gearing/dairy driver that can also tow. Any transmission will have to be pushed way back int he chassis because the engine is so long. This shoves the transfer case way back and you end up with a tiny rear driveshaft. Angles get bad and any lift just makes things exponentially worse.

Just because you have the engine for free, doesn't make it a good choice.
 
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