Tearing out my fathers 91 k2500 sub with 35 BFGs and 60's. The stock 350 just ain't cuttin it. I have bought a newly rebuilt marine motor and another 91 6.2 complete motor for the brackets and some other engine parts. I now need to know how I can mate a 4L80E to it and have a passenger side drop on the t-case. New to this forum so help is much appreciated. I think while I am at it I will propane and turbo it also. Any thoughts.

God Bless
Michael

As far as I know all Chevy bellhousings are the same (Buick Oldsmobile and Pontiac are the exception....BOP). A 4L80E that was behind a 350 will mate to a 6.2/6.5 or vice versa. You need to make sure you have the proper torque converter and flexplate however. As far as converting from a driver's side drop to a passenger's side drop, you will first have to decide what transfer case you want to use and then go from there (some are easier to adapt than others due to spline counts and factory mating practices). Advance Adapters can help you as well as the folks over at www.ck5.com (http://www.ck5.com) as several members have swapped t-cases behind 4l80's. I'm actually putting a 32 spline NP205 that was originally mated to a TH400 behind a 4L80 (passenger's side drop).


Tearing out my fathers 91 k2500 sub with 35 BFGs and 60's. The stock 350 just ain't cuttin it. I have bought a newly rebuilt marine motor and another 91 6.2 complete motor for the brackets and some other engine parts. I now need to know how I can mate a 4L80E to it and have a passenger side drop on the t-case. New to this forum so help is much appreciated. I think while I am at it I will propane and turbo it also. Any thoughts.

God Bless
Michael

Leadfoot,
I also have a NP205 in the sub now. how are you mating them together. Is the spline count the same and also how are you going to control the trans because it requires a computer to do it? Thanks and God Bless

Michael

There are several different versions of the NP205 out there (Ford, Chevy, and Dodge). Even within the GM line, there are several differences. There is the old figure eight style mount and the new round pattern mount. There are 10 spline male, 27 spline male, long 32 spline female, and short 32 spline input shafts. They are all 32 spline rear outputs (some fixed and some slip yoke.....fixed being the better of the two in my opinion), and the fronts came in 10 and 30 spline outputs (or you can swap in a ford 32 spline front outputs shaft as I did).

Here is some 205 tech: http://www.offroaddesign.com/NP205tech.htm


The best way is to start with an NP205 that was mated to a new TH400. It will have the proper input and the TH400 adapter can be mildly machined to fit the 4L80E as it has the same bolt pattern. It is also a shorter (in height) adapter which alleviates a stress point. I believe it's found only in 85+ 1 tons.

As for the controlling of the 4L80E, I plan to go this route: http://www.importperformancetrans.com/inventory.cgi?action=description&item_id=58.5818121885194


Leadfoot,
I also have a NP205 in the sub now. how are you mating them together. Is the spline count the same and also how are you going to control the trans because it requires a computer to do it? Thanks and God Bless

Michael