Will GM 200r4 work with factory floor shift location?

Treblig, your post has become a part of a-body history. You are a tenacious man with great talent and drive...overdrive!!!

I know some people would just bypass the radiator tank and go straight to an aftermarket cooler, but these cooler lines also warm the transmission up to safe operating temperatures more quickly too. Of course, after running through the radiator, I plan on going to an external auxiliary trans cooler as well to drop the temp even lower prior to its return to the transmission.

My latest question involves the cooler lines. I get that Mother Mopar has the smallest cooler line fittings at 1/8" NPT with the flare to the 5/16 cooler lines, while Chevy and Ford use the 1/4 " NPT with the flare to the 5/16" cooler lines. These fittings are located both on the transmission and on the lower radiator tank.

Here's the question, if they all use the 5/16" cooler lines, (without regard to the restriction the 1.8" NPT fittings Mopar uses) what size is the inside diameter to the internal radiator cooler? It must be at least 5/16" as well, right?

In other words, it's the fittings that screw into the Mopar transmissions and radiator cooler that are the only sources of restriction. Is that true?

I called US Radiator, and they seem willing to sell me just the 1/4" NPT "Chevy/Ford" sized internal , lower radiator tank "cooler/heater" to swap out the one that came in my custom radiator I bought from them for my Magnum install. They sure do nice work there. I never liked the look of aluminum radiators in these old Mopars. I can get a local shop to pop the lower tank off, swap out the internal cooler to the upsized fittings and solder it all back up for a nominal price.

Also, did you end up drilling out your fittings to match the inside diameter of the 5/16" line? In your experience, did it or would it take too much strength away from the fitting to open the inside diameter that much?

I just went out and took these pic. I also used the back of a drill bit to measure the inside diameter of the cooler fittings that came on my 200R4. I then measured the bit with an electronic dial caliper and came up with .220"

I'm sure the inside diameter of the 5/16 lines used on Mopar/Chevy and Ford are all larger than that. I'm going to have to go back into your post and see what size the 1/8" Mopar fittings is. I know I saw it in one of your posts.