[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?