NP435 or ZF5 in a 78-79 Bronco
 

Ok. I was debating on which to swap in my C6 79 (466 engine) Bronco. I was choosing the ZF5 since I will use this Bronco to drive on the highways BUT I would also go off-road with it. Nothing to wild. I'm hoping the ZF5 would get better MPG for my 466 since the RPM would be lower at higher speeds.

Which would be better?

-The NP435 will have the lowest first gear.
-The ZF5 will have the OD 5th gear but also a low first, but not as low as the first in the NP435.

-The NP435 is known to be bulletproof.
-The ZF5 is known to be ok for moderate stuff but the casing of the transmission is weak.

-The NP435 will be a simpler swap in the 79 Bronco.
-The ZF5 will require some modifications.

-The NP435 could handle the NP205 transfer case.
-The ZF5 would have to have the NP205 to have some braces due to the heaviness of the NP205. The Borg-Warner transfer case wouldn't and would have a lower gear in and be light BUT the NP205 could get lower gears in it.



Which would you do?


I'm wanting to determine before I do the swap. I'm thinking about the ZF5 and save the NP435 for my 79 F150 4X4. Let's see what yall have to say.

Personally I would always choose the strength of the 435 and the 205 over any combo. You can always change gearing if needed but its harder to build in strength. When in doubt go stout.

:-drink

Now I thought the ZF was claimed to be bulletproof? maybe the aluminum case ones weren't as strong? But I though that the Cast Iron ones were nearly bulletproof. I think I'd personally still go with a ZF but I've never worked with either and never heard of the BG one.

You made a good case for the NP435 Manfred, so I voted for that one, simplicity is key to this swap, and reliability is always a +. For my truck I would pick the ZF5 without a second guess, but mine is from the 92-96 gen.

Yeah, I was thinking about the NP435. I'm still kinda leaning to the ZF5 since I still have it. Let's see if more people can change my mind or keep me on the ZF5.


I liked the ZF5 that was in my 1990 Bronco but I don't know how good it will handle a 466....

These transmissions aren't particularly strong. Only Rated to 420 ft/lbs of torque (for the common s5-42), some are rated to 470 ft/lbs (s5-47, only 2 yrs production though and maybe only behind diesels but bell can be drilled to mount to 460). I dont know what kind of torque the Borg Warner was designed for but it was never meant to be behind a big block

Well I got to finish rebuilding the NP435. I have a 351m/400 Flywheel which should work. All I would need to do is:

Finish rebuilding the NP435
Get the crossmember for the NP435
Get the driveshaft for the NP435
Get the motor mount for the NP435



The reason why I was thinking about the ZF5 was because I would travel on the highways usually and I plan to keep this Bronco.


I don't know the MPG differences I would get between the ZF5 and NP435.