'88 1-Ton Crew Dually to SRW & T-400 to 4L80E Conversion

[Evil Trailblazer SS]

So I found an '88 4x4 dually that I am converting to a fleetside and I have a few questions and need resources to find what exactly I need to do to also get the trans swap to the 4L80E done seamlessly!

I have searched on here and various other site, but I haven't come up with much in depth details! I want to find out a few things before I jump head first into this...even though the trans and converter are already being built...

1. Is it possible to find refurb'd OEM Transmission control modules from 1991 or is it going to be easier to just run the new GMPP 19257661 Stand-alone TCU or even the TCI EZTCU? I guess another question would be, is the 1991 truck PCM a single computer that runs engine and transmission functions or are they separate? My only experience is with my old 1990 V3500 Crew Cab SRW (Turbo 400).

2. The whole shift lever assembly in the column, as far as the 4-speed indicator and all associated parts and hardware need to be sourced from a 1991 column or a 700-R4 column, has anyone made a list of the entire group of parts needed?

3. The main difference with external linkage is gonig to be finding a 4L80E shift linkage and that is it, correct?



Thanks in advance guys!

Steve