...Why would somebody do this?
Because for almost 40 years the NP435 was
THE transmission that everybody wished that Ford had put in the Bronco. But that was when almost everybody that bought a Bronco intended to take the time to go four-wheeling as often as time would allow. Not gaining any gears on top, but getting the slow gear was cool, and made up for crappy differential gearing when going with larger tires.
Some people even used first/low gear in the 435 on the street, because their other gearing was so bad for the tire size.
There were the toploader 4-speed street manuals, but they were few and far between and when found the street rod/hot rod crowd would snap them up and pay big bucks for them. Way out of the realm of most EB owners.
Never really took off because of the tall first gear and no overdrive for the money. Kind of cool to have good shifting characteristics, but spending all that dough and going through the motions to not end up with a low first gear was not in the cards for most EB owners.
The adapters have not been readily available for years, because not that many were sold even when Toploaders were considered a score.
Then the 5-speeds out of '80's Mustangs became a popular thing. For about a week...
They were not considered very strong, were a little long and finicky to make fit into the Bronco packaging for minimal gain. Overdrive wasn't as big a thing just then as the low first was, but it was gaining ground. And while smooth shifting, had horridly tall first gears. The opposite of what most people wanted with their Broncos.
It wasn't until the NV4500 became a thing that we started believing that there was light at the end of the transmission tunnel again. You could get your granny gear
AND an overdrive, with the usual three speeds in the middle. And it was strong and almost as reliable as the NP435. Though never as inexpensive as one unfortunately.
And they were physically huge for the benefit though. An NP fit like a glove almost, while an NV needed lots of tweaking and adapting (money) to make fit. And even then, at such a more recent time, not everybody was on the whole "let's fabricate a new vehicle to fit around the transmission" kind of work ethic. A few clever individuals were ahead of the curve there (as always), but most of the masses just wanted a bolt-in and go kind of thing.
Enter the NV3550 and now the AX15 and bingo! Relatively strong, not a super low first gear, but definitely a better first gear than stock, and an overdrive all in a small-ish package. Still expensive, but by then folks were pouring money into their Broncos like there was no tomorrow.
And by then the granny low wasn't as needed as an overdrive, and more were spending the money on differential gear changes anyway. Or low gears in the transfer case. Many Atlas' were sold in this period. Costing more for just the gearbox than most EB's cost the current owner!
There were others thrown into the mix of course. ZF5's out of Fords for example, but relatively unknown compared to the others, and again, very large, so needing more work even if fewer adapters.
So those were some of the highlights.
Now things are coming around to a different type of owner and use and expectation. But for those last 40-50 years, lots of previous owners had lots of different wants and needs. Maybe they had a need for an off-road rig, or maybe just had a free NP laying around.
Since you like old-school feel and may not have a wide range of needs for the Bronco, an NP with a GearBanger shifter would certainly be fun. For a time...
But it's yours already, and that counts for a lot perhaps.
You would probably be happier with a newer manual, or an automatic from the sound of your intended use. But if the NP is already there and you want to move on, nothing wrong with keeping the old strong and reliable in there.
For now at least.
Might ultimately come down to what gearing is in your differential and what tire size you will use when driving on the street. An overdrive might not even be compatible with what you have. Then again, if the PO installed 4.88's and you're wanting to run 31" tires, you would be ahead of the game by changing to an overdrive instead of changing the differential gears.
Even with a good existing unit, there always seem to be lots of choices and options!
Paul
