Same as Clois/Paul for me, running a 47 year old toploader,had it gone thru 8 or 9 years ago, it is in my road race car, running races from 15 to 30 minutes of all out racing as hard as I can, never have had any problems, soo far, knock on wood!!!!!!!!!!!!!!
It will and does get hot at a track session, I've put my hand on the case just to see,but never have had a shifting problem from cold start to the end of a 30 minute race.........
I use 75/90 Valvoline gear
oil in as per the guy that rebuilt it.......I change the
oil in it at the start of each race season,thats all I've done to it in 8 racing seasons.....
David