I am mounting a A518 behind my mild built 318 and was going to plumb the cooler lines into the bottom of the radiator but after reading some posts about these trans running hot in OD am thinking maybe I should add a transmission cooler to my aluminum radiator. This will never pull a trailer so wha are your thoughts on keeping it cool.

As you know heat is the killer of automatics. I'd definitely add the largest cooler that will fit. some keep the bottom tank rad cooler in series with an aftermarket cooler to heat the fluid in the wintertime. Me I use only an aftermarket cooler the largest one that will fit. No problems in the dead of winter & I certainly dont romp on anything when it is cold

most of the aftermarket transmission suppliers also require you to run a seperate transmission cooler and bypass the one in the rad.

prevents any possible way for you to get a leak in that cooler and suck up coolant.

For Pennsylvania winters I'd run the aux cooler downstream of the radiator cooler.

Thanks

I was thinking of adding it after the rad. on the return line.

My trans is a 92 but after 93 they also added a check valve to the return line any idea of why that was done.

The check valve prevents the cooler in side-tank radiators from draining into the trans.

If I instal a 10" high cooler to the front of the radiator with pressure in the top and the return line out the bottom do you think I should also put a check valve on the system or could mounting the cooler vertical with pressure and return both on top solve the drain back.

Check valves can be a source of problems; to deal with the drainback problem just get in the habit of starting the engine in Neutral instead of Park.