swapping 4l60e's

[ItSSlowZ28]

this is what EFIconnection told me in regard to the 24x swap. :

I wouldn't dismiss the LS1 PCM because you have an early 4L60E. Updating a 94-95 4L60E to 96-newer electronics does not require a transmission rebuild. As I understand it, you're looking at a valvebody swap, electronic solenoids swap, and internal harness.

their website says the ls1 pcm can't control the early 4l60e's because the internal electronics are different. i'm not sure why the 95 lt1 computer would work with a 96-up trans and the ls1 pcm wouldn't...

[rdx]

I swapped a 95 4L60e into my 96 Formula, all I did was to swap the tailhouse and VSS sensor, I didn't swap the wiring harness, I'm now having some issues when idling when in gear, could this be related to not swapping the solenoids and wiring?