[grivera]

Reviving old thread-considering a 4L80e as a winter/off season 2022 project. How much farther back does tail shaft sit? Are the pre-1996 transmissions the best way to go?

[TedRamAirII]

I believe Gary Harrison has.

[Sirrotica]

Originally Posted by grivera

Reviving old thread-considering a 4L80e as a winter/off season 2022 project. How much farther back does tail shaft sit? Are the pre-1996 transmissions the best way to go?

Here is a table of all the automatic transmission measurements:

https://transmissioncenter.net/shop/...-measurements/

4L80E 2 WD standard length 32 11/16"

Short tail T 400 28 3/8"

By my math, 4 5/16" longer.

It has been mentioned that the earlier cores have more less clearance problems with cooling line, tunnel clearance than the later ones. There is a kit to use with the later transmissions to help with the clearance problem.

Banjo fittings to go to 6AN hoses on late 4L80E: https://www.ebay.com/itm/16435874270...RoCHyUQAvD_BwE

[grivera]

Originally Posted by punkin

I had hoped to be a little further along in my rebuild but I do have a fresh 4L80e for my 68 firebird sitting in the garage. I went to Jakes Performance. They advised this is very doable and told me I should be able to avoid any modifications and hassles if I went with the earlier version of the 4L80e. The coolant passages are in same/similar location as the TH400.

Good to know - which x-member are you gonna use?

Originally Posted by Sirrotica

Here is a table of all the automatic transmission measurements:

https://transmissioncenter.net/shop/...-measurements/

4L80E 2 WD standard length 32 11/16"

Short tail T 400 28 3/8"

By my math, 4 5/16" longer.

It has been mentioned that the earlier cores have more less clearance problems with cooling line, tunnel clearance than the later ones. There is a kit to use with the later transmissions to help with the clearance problem.

Banjo fittings to go to 6AN hoses on late 4L80E: https://www.ebay.com/itm/16435874270...RoCHyUQAvD_BwE

Thanks for the info. Any idea if the HD unit can be used? Also, I assume the adapter plate will add at least another 1/8" - 3/8" so about 4.5" longer?

Also, I read in another thread one has to clearance the trans tunnel a bit to clear trans lines. Do the 90 degree fittings provide the adequate clearance without banging on the tunnel?

[Sirrotica]

The HD originally has the parking brake on the rear of the transmission because the HD trucks have 4 wheel disc brakes. I actually own one of these trucks, but have never taken all the parking brake parts off to see what's under it. I'm still moving stuff from my old house to the new one and using this truck with electric gate, and box body to move, so I can't answer that question.

I've never seen anything in print that you can't use the HD transmission, maybe a call/E mail to Jake's would give you the answer about what parts are different , if any on the HD transmissions.

I did a quick search and found this about output shafts:

https://ls1tech.com/forums/automatic...-variants.html

I also found this, and it says that the HD version is actually a beter candidate because some of the better parts in the transmissions:

https://ls1tech.com/forums/automatic...-4x4-swap.html

I guess I'll be looking for the HD/motorhome versions from here on out....