Getting a bench rebuild on the tranny but need to know how to flush the rad/lines when/before I put the new one in..........help?

 

While the trans is out..... just run some flavor of solvent thru the lines. When the solvent runs clean, run fresh trans fluid thru, to clear out the solvent. (don't use anything too rude though....)

What kind of facilities do you have available to you? It can be as simple as a funnel stuck in the end of one of the lines, to making up a pressure cleaner. (just watch the pressure. )

 

bypass the radiator cooler. Install aftermarket cooler. Cut out the check valve.