i just recently did a 5.3 4l60e swap in my 92 swb truck for some reason 1 2 gears shift fine but when it tries to shift into 3rd the motor just revs freely i have already tried replacing the 2-3 shift soleniod and when i unplug the trans it defaults into to 3rd gear and takes off in 3rd gear thanks

 

ya im pretty sure i have all the pulgins hooked up on the trans mission

 

Sounds like the 3-4s are burned up.