What kind of a adapter do i need to put a 205 behind a 4l80e tranny? I need the 4l80 to handle the ramjet 502 I am planning to put in the 72 3/4 ton 4x4 suburban. :usa:

You need the same adapter that is used for the TH400/NP205 application. You will need to machine the adapter to accept the O-Ring from the 4L80E, and will need to change the 205 input shaft to the longer version.

Also, you will most likely need to cut about 1/2" off the end of the 4L80E output shaft to ensure that it doesn't bottom-out in the t-case input shaft.

Other issues to consider include shift linkage, moving the crossmember back a bit, plus the necessary computer, but you probably know that already.

I have this combo in my '73 Suburban, and can supply you with part numbers and more detail, if you like.

Just let me know...

Robb

please send any info you might have. I found a tranny shop that said they can build a 4l80 with a vacuumn controler and not use a computer. or i might a jet transmission with the controller for a not computer control truck.

I don't have access to the part numbers from where I am right now, but I'll dig the info out later today and post for you.

I would suggest that before you go with the vacuum modulator setup, you might want to talk to some people that the shop has done that for in the past. I've heard of that mod before, but with mixed feedback about how well it works.

If you decide to go with an ECM controller, you may want to take a look at TCI's unit. I like it a lot better than the Jet controller. Although I'm running a Jet trans, I went with the TCI ECM because it has much stronger configuration capabilities, and you can program it yourself instead of relying on Jet's standard setup.

All you need to run it is a TPS (which can be adapted to a carb setup pretty easily), a speed signal, and an rpm signal. It's super easy to program, too.

Robb

Sorry it took a while to get back to ya with the part numbers. They turned out to be harder to find than I thought.

Adapter: GM #14022218
This is the standard TH400 - NP205 adapter. As I said before, you need to machine it to fit the back of the 4L80E with the O-Ring seal. Once you have the transmission, it will be easy to tell what's needed.

Input Shaft: GM #15594158
This is the longer NP205 input shaft, which will give you better engagement with the 4L80E output shaft.

Here's the disclaimer: please make sure to double check the part numbers with your GM parts counterperson. I had to dig for these numbers, and I'm 99% sure they're the correct ones. Just don't want you to order the wrong thing.

Enjoy,
Robb

Hey Robb, sounds like the '85 to '91 NP205 with the round-bolt pattern. Correct?

Hey Cory. Not sure if you are referring to the adapter or the input shaft. The adapter is the old-style hourglass (or figure-8), but I believe that the input shaft may be from a later-model round bolt-pattern t-case.

In my combination, I had the older-style NP205 and adapted it to the 4L80E. If I misunderstood your question, just let me know.:)

Robb