I have been doing a lot of reading on here and have learned a tremendous amount. There are some guys out there who really know there stuff and hopefully some you read this and will be willing to help me out. I have a 1979 F-150 Custom 2wd w/302 and a RUG (SMOD) 4spd with Overdrive. The truck only has 38,000 miles on it but thrust bearing has gone out of it. I am fixing the thrust bearing and crank but while I'm at it I was thinking about taking out the SMOD and putting in a NP435. The SMOD first gear is just way too high geared. Your practically burnout the clutch just getting it moving on level ground. I know the SMOD was part of the reason the trust bearin when out of it. I have been doing a lot of reading and it sould like the SMOD is a pile of junk. My dad said it always was. We used to have a 1979 f-150 w/300-6 and NP 435 and I loved it. I loved the granny 1st gear and they are bullet proof. From what I have been reading it is clean swap from a SMOD to a NP435. I know I am sacraficing gas milage taking out the OD but that don't matter to me much. I wanted to know is it a "real true swap" Do I need to change anything within the bellhousing or the bellhousing itself. Will it bolt directly to same holes on bellhousing without shimes. Will my old drive shaft mate with the NP435? Will the splines match or will it have to be cut or lengthend? I know there is a 4 wheel and a 2 wheel version of the NP435. My truck is a 2 wheel. Will a 4 wheel work? From what I hear only difference between a 2 and 4 wheel NP435 is bolt pattern on rear of tranny case wear the tranfer case is suppose to bolt. If I don't have a transfer case will this matter? How about my cab floor. Will the NP435 shifter fit through the original hole as the SMOD or will I have to change that? Are there any changes to the transmission mounts/crossmembers? Thanks for taking time to read this. Please help me if you can.


flyhound

 

I've converted both my 81 and 82 F100's, using the same transission...
Here is what you will need:
A 2wd NP 435, preferably with a rear slip yoke output, like this:

The floor plate out of a truck with a NP 435(to re-locate the shifter hole,) the slip yoke from it's driveshaft(or just grab the whole thing if you find a donor truck with the same wheelbase) and IIRC, you will need to change the speedometer gear.
If your donor truck is the same wheelbase and has a fixed yoke 435, use it with it's driveshaft.
A 4wd NP 435 will not work for your application..

Take a look at my 3.03 to NP 435 article in the Tech Articles section. Just skip that parts about hacking up the floor and changing the speedometer cable.
https://www.ford-trucks.com/articles.../transswap.php

 

Ok so I need new floor pan, a 2wheel NP435, No problem other than tearing up nice floor mat and finding a two NP435. I live in NW MN. Not many 2 wheels drives up here. 4 wheel is necessaty 10 months out of year. I will have to do some measuring. I think slip yoke same slip yoke might work for both NP435 and SMOD. I think shafts are same size and both trannys are about same length. Speedo gear I can understand, what is all involved in that? And what do you mean by IIRC. Does anyone else know if any mounts, or anything with bellhousing has to change. Doesn't sound like it from what I read

 

Is your SMOD an aluminum case internally shifted unit, or an iron case external shift unit? I know the aluminum case ones have the smaller C4/3.03 sized yoke, and, I've never seen an iron case one in person.
IIRC = If I recall correctly.
On the 80-up trucks you need to turn the transmission crossmember around so that the mount will line up properly(both use the same mount), and, I'd imagine the older trucks worked along the same lines.
As for the bellhousing and clutch, nothing has to change.
Good luck
Evan

 

Thanks Evan,

I'm pretty sure it is a iron case. The SMOD stand for Side Mount Overdrive. It is and external shift with the shift rails on the left side. I did some reading though on the NP435. It said that some 4x4 used 2wd 435's if transfer case wasn't married. From pictures I have seen the output shaft slides into a gear in the trasfer case. The transer case and tranny aren't bolted together.

 

Yes, the divorced transfer case setups(primarily 77 and older) use a fixed yoke output on the NP 435, like a fixed yoke 2wd setup. These use a shaft with a slip yoke in a 2wd application, I'd imagine a Divorced setup also uses one, although a rather short one.