6 speed?

[thusley]

building a 84 chevy truck
im using a ls 5.7 but for durability I would like to use a
6 speed automatic out of a newer truck
anyone made this swap yet any ideas on simplifying the
process and the control module?

[kerrige]

The process to make a 6L90e swap work is incredibly expensive and difficult. The 4L80e swap is arguably more reliable cheaper and easier.

[George C]

if you find a complete donor harness that should be the easiest way

[thusley]

I haven't really started researching it yet but I'm not a 4l80 fan I would much rather ues the 6 speed
and I have a engine harness that has some rodent damage in the engine area really wouldn't be that hard to fix
but I'm not sure the pcm will work with the older ls motor and sensors building the older pcm connector would be a job and then what about trans control?

[George C]

have the reluctor wheel swapped over on the ls1, this way you can run the new pcm

[kerrige]

Just so we are clear.... what makes you want to use a 6speed? They don't have anyway really of beefing them up at this point. The 6L80e requires a sperate TCM. They can't hold big big power as evidenced by just about anyone with more than 700hp. (Chevrolade and silver sleeper both proved that) It is a good transmission that isn't worth the extra cost and effort. I would rather do a TH400 and GV every time. Giving you basically a solid mechanical controlled setup that is DD/highway friendly.