I was thinking of swapping out my NP435 for ? Maybe a five speed or something.

The question is what other transmissions would fit, or be a bolt up if at all possible.
I'm running with a 1978 F250 4x4 with big block 400, NP435 trans with aNP205 transfer case.

Any suggestions comments are welcome.

 

A 460 2wd zf5 may fit in there. '78 was divorced, correct? I assume you're looking for an overdrive? A T19 is a good gearbox too. No overdrive but may be easier.

 

Thanks,
No it is not divorced.
Yes I am looking for some thing like that. it seems to me that I run out of gears before the engine is done providing power.

 

It can be done, but there are issues with the crankshaft end of things. Exhaustive explanations etc here:

https://www.ford-trucks.com/forums/1...-zf5-swap.html

 

What axle gears do you have?

 

Here is a little info, I'm thinking you can do the 4X4 with a little googling.
Installing the NV4500 Overdrive Transmission - Ford-Trucks.com

 

I have the 4:10 ratio in the rear and 4:09 up front.

 

That'll do it! Great gears for an overdrive! You could change to 3.55s. They seem to be a good all around gear for an overdrive or direct. Might be cheaper than doing a transmission swap. They did make an overdrive in the 80s that was a 4 speed. Not sure if youve heard of it SROD. They are not the most liked gearbox, but should drop right in (someone correct me if I am wrong). After looking at the link that
85e150six4mtod posted, I dont know if there would be an input shaft issue or not.

 

I'm in the process of a ZF5 swap. If you have a 460 its not too much work. Move the crossmember back ~4.5" install, new driveshafts all around if you have married T-case, run hydraulic stuff good to go. You just don't have a speedometer signal anymore unless you use NP205. ZF5 era trucks got their speed signal from the rear differential (Sterling 10.25/10.5)