Had the transmission rebuilt by a pro a couple years ago, replaced everything easily sourced, polished gears etc.
Have filled it with Dino 90W gear oil. Have issues if rpm's aren't exactly matched shifting into 3rd. Upshifting or downshifting.
Was reading a post about "bench testing sm420" and Jerry mentioned 90W Ford tractor oil. Anything I should look for, and would my dino oil be okay for it? Son's a heavy equipment operator and gets it free from work as it's used in his Cats.
