6l90E 2wd 36 spline to 4X4 NP205 27 spline drive coupling idea???

[NDM]

I am moving this post to what should be the correct area.

I am curious why this idea that I have would not work. Please check my proposed idea.

I have my 72 that is getting a Gen V L8t 6.6 swap. Currently I am 4x4 but my new trans is 2wd 6l90e. I know I could find a 4x4 trans. I know I could convert the 6l90e to 4wd. But..... why could I not simply buy a new 27spline to 27 spline th350 to np205 drive coupler for about $50 and take it to a machine shop to have it resplined to 36 spline (to match the 6l90E). Then simply fabricate the required spacer/ adapter tube to bolt the two together like the timberline no cut adapter kit (1800 bucks). I am a welder/ fabricator so the adapter is not a problem.

Here is the replacement drive sleeve but I can get one much cheaper elsewhere. https://www.offroaddesign.com/drive-...27-spline.html

I am trying to retain the ability to go back to my SBC 350 in the future if I so desired. Once I machine my np205, no going back. Also, I really want to run my 6l90E. The modern motor and trans have 25k miles and were from the same truck. I am building a daily driver with the option for some future owner to go back to the OEM parts if they want to.

Why would my idea NOT WORK?

Fyi, for anyone wondering why not just buy the timberline kit.
1. It is $1800 (I am currently laid off from work)
2. It still requires machining the np205.
3. It comes with a male/female adapter and I need a female/female adapter.

Also, the parts and tools required to convert my 2wd 6l90e to 4x4 is about $400. I could pay the machine shop and still have cash for the material required to build the adapter tube for $400.

Here is the timberline adapter tube thing that I would fab up on my own.
https://timberlinesupply.com/product...conversion-kit

[LS short box]

You might try Novak conversions in UT or Advance Adapters I believe out of CA.
I used Novak to supply the parts to adapt the 4L60E to the 241R in my 98 Wrangler with a LS6.

[NDM]

After thinking about this a little more, I came up with a second idea. If I buy a used NP205 case with a 32 spline female input shaft wouldn't I be able to have it re-splined to 36 spline to match the 2wd 6l90e? I could then mate the new np205 to the trans and save a little room in the middle. This will still require an adapter to be made but I could save a few inches and it would be even more stout considering that the lowest spline count would be 36 spline.

Please remember that I am brainstorming here and maybe this could help out some poor guy in the future that is in the same situation.

[NDM]

Originally Posted by LS short box

You might try Novak conversions in UT or Advance Adapters I believe out of CA.
I used Novak to supply the parts to adapt the 4L60E to the 241R in my 98 Wrangler with a LS6.

I checked all over their site and did not se anything. I may call them next week.
Thank you!

[Richard]

The 6L90 in the ZL1 came with a 32 spline output, it is available. A 32 spline female input gear is available. As my motor and trans is from a ZL1, used the Advance kit and it bolted together with a bit of trimming on the output shaft and 32 spline input to t-case. Understand wanting to keep stock stuff intact, do this myself. Had to really think about whether I would have the time, resources or ability in the future to return my truck to stock. For me the answer is no. I still have my stock transfercase as I had my dad's original case bored for the larger female input bearing. Wanted to keep mine for spare parts, do not see it ever going back in the truck. There are some pictures of the install in my build thread. Back of the 6L90 transmission needs two plugs and a seal installed once the tailhousing is removed to hold the oil in it. The adapter runs dry.

[NDM]

Originally Posted by Richard

The 6L90 in the ZL1 came with a 32 spline output, it is available. A 32 spline female input gear is available. As my motor and trans is from a ZL1, used the Advance kit and it bolted together with a bit of trimming on the output shaft and 32 spline input to t-case. Understand wanting to keep stock stuff intact, do this myself. Had to really think about whether I would have the time, resources or ability in the future to return my truck to stock. For me the answer is no. I still have my stock transfercase as I had my dad's original case bored for the larger female input bearing. Wanted to keep mine for spare parts, do not see it ever going back in the truck. There are some pictures of the install in my build thread. Back of the 6L90 transmission needs two plugs and a seal installed once the tailhousing is removed to hold the oil in it. The adapter runs dry.

You are right but I just got it into my head that one day this truck may be a smoking hot buy in it's original form. I guess I am just being goofy about it. I will look for another case that is possibly already 32 spline.

Truth be told, I did not even want a 4x4. I found my Blazer and planned to convert to 2wd and autocross style. Somehow, I have grown to love the thing up high. I then started to think about the utility of having it as 4x4 and still having the buttload of power that I am going to put in it. I picture driving in the mountains and sand near my parent's property in Arizona. There is plenty of desert fun to be had. 34.732789992951936, -114.09279412633629

If I can work out retaining 4wd I will but I could also either do lifted 2wd as a prerunner style or drop it down low as a track star. Whichever way I go, I have a feeling that I will love it for many years to come. This is in fact my "Bucketlist Blazer".

[57taskforce]

All The th400 and late 85+ GM sm465 205’s are all 32 spline big bearing inputs if that helps. The 85+ 205’s are the best, strongest, and most sought after.

I can’t see why this wouldn’t work as long as you got the shafts coupled together. It’s really no different than the spacer that goes on the back of 700r4 to mount a th350 Np205 to it. (there’s a bit more to that conversion but the end result is the same)