Np 205 questions

[57taskforce]

I've got some questions about the 205 case. First a little info about my truck. It's 1957 chevy on an 88 k-5 frame (yes I know by 88 they used the r/v designations) it's got a mild 350 with a vette spec 700r and 208 case. 14 bolt ff rear and 3/4 ton cooperate 10 front. 4" suspension lift and custom cab mounts that combined easily clear 35's... I'm in the planning/gathering stages of a semi major drive train build up. To include: gm dana 60 front, 205 case and I'm hoping for a 4l80e. I've got the 205,turbo 350, and the 350 adapter and crossmember from a 72 k10.(I have no desire to run the th350 or 700r with the 205) My question is what do I need to do short of the advance adapters kit, and the holy grail 1991 80e to 205 adapter, to mate a 205 to an 80e? I've done a ton of reading from pirate,ck5, and a few other boards but everything I've read seems to contradict in some way or another. I realize to use the 205 I've got I need to replace the input gear,bearing and machine the case which isn't a big deal. I'm more worried about how the hell to mate the two. So I'd like to hear from people who have done this swap. I'd rather avoid the he said, she said, and hear it straight from those who have done the swap. I want to know what length output 80e you used, which 205(racetrack or round) and how you mated the two? Thanks in advance and I'm sorry for all the reading!

[franken]

Advance adaptors has a conversion guide they'll send or you can probably download it.
It says you need the 50-0410 adapter for the 8 bolt NP205 plus the new input and machining you mention, as well as another output shaft for the trans.
I'd think that a 4L80 is a 32 spline output and a 4x4 version has the same round bolt pattern as a round NP205, but I have no first hand experience.

[57taskforce]

They do have the 32 spline output shaft. I should have mentioned if at all possible I'm trying to stay away from aa just because of their crazy prices. I've read some people modifying the th400 tall mount to work but then I've also read other people say the same thing didn't work for them. I guess half the problem is most of the threads are old enough that the pictures don't work so it's all guessing for me with no pictures.

[franken]

The AA kit is $568 and includes the short input and bearing.
What input is your 205?

I'd be looking into 4x4 trans and start hunting a round 32 spline 205.

[57taskforce]

Mine is the 27 spline th350, which is why I need to swap in the female 32 spline input gear. I've also read people were able to machine an O ring groove into the th400 mount and other than that and some cutting on the output shaft of the 80e they bolted up. It just seems like the threads I read either didn't have any pictures or they were full of seemingly less than credible info. I plan to use the ORD twin stick kit, and modified shift rails to allow for the added feature of front wheel drive, so I'm trying to mate the two together as cheap as possible.

[franken]

Sorry to keep posting w/o helping...

Well, one of the bolt holes in the round adapter and one in the round pattern NP205 is offset slightly, if that makes sense. It seems the round pattern is a standard, but where the offset hole is is not standard. I've been told it's not even consistent within various TCs used in GM applications.

If you want to figure out where the offset hole is on a 4l80 adapter, I can get the same info from my round NP205. The easy way to do this is get a round 6 hole gasket and match it up. It may be that some adapters or tailhousings are different depending on the TC used, and/or the side of the drop.

If the clocking is is the same, you can get a 4x4 4L80 with the adapter, and a round pattern 205, a short input, and sell the 205 you have.

I suspect this will be the cheapest route.

I parted an 89 Suburban to get the TC I have so I understand they are somewhat rare.

I snapped a few pics showing how the gasket fits. PM an email address if you want them. Too big to post and too small once scaled.

There's an extra hole in the gasket I have. I'm not sure if its on all of them. The extra hole in mine ends up right over the inner shift rail. Note that since the gasket is asymmetrical, it only fits when flipped the right way.

[franken]

Have you looked at this?

www.trailtechfab.com
Which leads here:
http://www.pirate4x4.com/forum/motor...ngagement.html

Title: "Infinitely clockable GM T-case adapter kits replaces stock full spline engagement!"

[57taskforce]

thanks for taking the time to reply and look around. I had seen pictures of the weld up mount but didn't honestly pay as much attention as I should have. After looking thru your link I think I will go this route looks easy enough and I'm handy with a welder. Thanks for bringing this to my attention! I'd still like to see your setup so I'll on you an email address. Thanks again!

[franken]

I'll send some pics.

I saw 2 possibly round pattern NP205s in a search of NP205 on CL in Farmerville or something like that.

If you can find a round pattern with a long input you may be able to cut the input down some. AA also has a 1.75" thick round pattern spacer commonly used when mating a long input 205 to an NV4500.

I see on ebay that there's a big bearing 8 bolt empty case for $99 (no idea what machining a case costs), and short 32 sline shafts are $150. The bearing is expensive...

I saw a post on pirate that made a brief reference to using a 4L80 to NP241 adapter.

[Mr. 250r]

Call offroad design they will know i asked them this as well awhile back since i didn't want to pay big money for the 91 adapter i did find

[57taskforce]

Wow I'm glad some one has seen one in real life. I was beginning to think they were mythical! I'm gonna order my twin stick setup and shift rails from ORD so when I do I will ask about adapting the case and trans together. I'm still trying to plan this all out, I'm not actually In the buying phase yet.(got my first baby due in a few months so I'm trying to get everthing ready for her) but after that it's game on.