The 90 chevy 1/2 ton truck came with either 700R4 or a 4L60E. If it is the 4L60E it will bolt up but since it is an electronically operated unit you will need a stand alone computer that you can purchase from GM Performance Parts. Also, double check the spline count on the output shaft to see if its the same as your old one, which should be 28 splines. If you run into problems, contact Advance Adapters on the web or call them. They are in Paso Robles,CA.Have fun!