NP-435 differences?
Thread Starter
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Senior User
Joined: Sep 2003
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Please help with hiboy tranny replacement
Hello, this is for a stock 1973 F-250 4x4. It has a 390 with a New Process 435 four speed behind it. It is the divorced unit. I need to put in a new tranny, and my friend has a NP-435 that he dropped from behind a 400 engine that was in a 1977 F-250 2x4. I don't know if the NP-435 that was behind the 400 is the same as the one that was behind my 390. No idea if the input shaft is the same or it will bolt right up. Please help and thank you.
Thread Starter
|
Senior User
Joined: Sep 2003
Posts: 305
Likes: 0
NP-435 differences?
Hello, this is for a stock 1973 F-250 4x4. It has a 390 with a New Process 435 four speed behind it. It is the divorced unit. I need to put in a new tranny, and my friend has a NP-435 that he dropped from behind a 400 engine that was in a 1977 F-250 2x4. I don't know if the NP-435 that was behind the 400 is the same as the one that was behind my 390. No idea if the input shaft is the same or it will bolt right up. Please help and thank you.
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
I think your asking if it will bolt up to the bellhousing, yes.
Now, as far as the input shaft spline count, size, and depth, I usually hear that all the Fords are the same and will swap around. The diffrences are between the 2x4/4x4 versions and thats with the rear bolt patterns/spline count on the output shaft.
BUT, I've also heard that FE's NP-435's input shaft is larger and only 10 spline whereas all the other Ford NP-435s had a slightly smaller shaft and more splines. This is what could prevent you from bolting a NP-435 from behind a 400 and mating it to an FE. I don't know this is fact, but you've picqued my curiousity. I'm gonna ask around and get back on this one. Hopefully somebody who already knows for sure will chime in.
Now, as far as the input shaft spline count, size, and depth, I usually hear that all the Fords are the same and will swap around. The diffrences are between the 2x4/4x4 versions and thats with the rear bolt patterns/spline count on the output shaft.
BUT, I've also heard that FE's NP-435's input shaft is larger and only 10 spline whereas all the other Ford NP-435s had a slightly smaller shaft and more splines. This is what could prevent you from bolting a NP-435 from behind a 400 and mating it to an FE. I don't know this is fact, but you've picqued my curiousity. I'm gonna ask around and get back on this one. Hopefully somebody who already knows for sure will chime in.
Last edited by proeliator; Feb 7, 2004 at 10:39 PM.
Post Fiend
Joined: Sep 2000
Posts: 8,238
Likes: 3
From: Oregon
Okay man, your thread was moved from the '73 forum so I hope you find this. Anyways, it seems as if the old 352FEs in the 60's used an NP-435 that had a longer input shaft. However, aside from this exception all the Ford NP-435s had the same 6.5 input and will interchange. In other words, you are fine 
