The electronics should not matter as long as your manual transfer case has no speed sensors. You might be able to swap 4l80s with someone that has a 4x4 and needs 2wd. Its a long shot though. You will have to change the input shaft in the transfer case to be able to mate to 4l80. EADperformance.com has the gears for your swap. I dont know exactly what you have to do to make the 4l80 into 4x4.
The links below may help.
ECSB 4WD 4l60E to 4l80E - PerformanceTrucks.net Forums
Transfercase input shaft swap write-up. - PerformanceTrucks.net Forums
Also at the last link are several stickys on the subject.
GM Drivetrain & Suspension - PerformanceTrucks.net Forums