I have a 90 K1500 5-spd(HM-290) that the over/under shaft went out on. It seems spendy to get the shaft when i will be doing a motor swap in the very near future. I am planning on building a torquey 383 build with a taget torque around 450-475 lb/ft. Since the trans is already going out right mated to the stock 350 TBI motor, it only makes since to replace it with the upgraded trans now in expectance of the new motor. I have read that the NV4500 is only rated at 450 lb/ft. of torque so I wouldn't feel comfortable putting it knowing that a constant rebuild was my destiny. i have been lookng at the T-56's and the ZF-6, but would like to know if it would bolt to a 350 TBI block. I will be doing the 383 build based on the TBI Block. any input is appreciated. Thanks in advance my forum brothers. The truck is 4WD with the F44 package so my rearend will hold the power.