Auto Trans Question

I'm getting closer to breaking in my engine on a run stand. So question is, in your opinion would it be ok to just plug the transmission where the lines (cooler ) come out of the tranny ? or do I need to hook then up to the radiator during the break in period ?? Thanks , Kevin

If the radiator on the test stand has a cooler, hook it up. Don't plug the ports; at the least, hook the ports together so fluid will flow.

+3...gotta have a completed circuit. Even if it's just a short piece of tubing.

if it were me, i would hook a cooler to the lines.
any junkyard unit would work, however, MAKE SURE IT FLOWS FREELY, AND IS CLEAN, CLEAN, CLEAN, INTERNALLY !
just my opinion.
your mileage will vary.