This question always sparks a debate. Its like the "what motor oil should I use" question

I can say through experience that when we ran a 727 in the race car it really didn't care what fluid was in it. We ran Type F, Dex/Merc, ATF+4, John Deere hydraulic oil, Universal ATF etc...….etc.....etc...… The trans really didn't seem to care. It always performed well and always looked good when we would tear down for inspection and freshen. The last 727 we ran went for 6 seasons (over 750 1/4 mile passes) and still looked good inside when we tore it down. I think having good internals and proper assembly and clearances is much more important than the type of fluid.

Pick something...Cause what ever you choose, it will be all over the floor over the winter as the car sits and experiences converter drain back. It will give you the opportunity to drain and try something else as you chase the leaks. LOL!

Every leak has a cure It is up to you to find and fix it
My race cars that sit from early Sept. to late April the next year don't leak any fluids, you can make your cars not leak also

transgo no yo yo kit stops drain back.

Nothing "stops" drainback..the Transgo kit just allows refill in Park.

Don't those kits allow the pump to flow fluid in park also?

If the crankshaft is turning, the pump is pumping but, in Park, some of the output flows out the manual valve and converter refill is slow. The TG valve seals off the manual valve so the converter refills quicker.