Trans and wiring questions

[Scott2]

I'm collecting parts to do an LS swap into my 1951 1/2 ton. So far I have a 2006 LQ4 6.0 engine out of a Silverado 2500 truck. I am looking for a 4L80e trans to go with it but haven't had much luck finding a good one.

First question - The local salvage yard where I got the engine has several older trannies - roughly 1998 or so - that they are offering. One example has 156k and is about $700.

I know there is a slight difference in bolt pattern to the motor but it appears that it will bolt up fine. Are these trannies a good option? What do I need to look for? Are these likely to be in workable condition with this mileage?

Second question - the engine came with a full stock wiring harness, computer, DBW gas pedal, air box, etc. I was also offered a reworked harness - brand new and set up for an ~2002 6.0/4L80e with drive by cable for $500.

Does this make sense? I'm definitely not interested in modifying the original one myself but I could likely sell it.

Thoughts or advice on either issue?

Thanks!
Scott