I recently replaced the transmission in my 2000 Chevy 1500 Silverado with a known good used transmission, ( I watched it drive through the yard and onto the lift ). I installed a new torque converter (pre-filled) and changed the filter for install. Made sure the torque converter was properly seated.
Install was smooth, no problems with fit. Filled the transmission with fluid and started. No strange noises, checked and filled to proper level after fluid level dropped.
Went to run it through the gears and it won’t turn the wheels in any gear. Engine rpms will drop when I put it into gear but won’t turn the wheels.
Transfer case is in 2 high, brakes are released, we even removed the drive lines to see if the output shafts would spin, no luck.
Im getting pump flow at the trans cooler.
Im lost as to what is wrong.
Any help is appreciated