Excess fluid in tailshaft

Hi Everyone,
We have a 1970 slant six three on the tree Dart that we rescued from a 30 year slumber last year. The problem is with the transmission. It is that base 3 speed New Process A 903. Anyway, put a new output shaft seal, and output shaft sleeve. Still leaks a bit.
My question is why the tailshaft is FULL of trans. Fluid? Is that normal? If not, what is the fix?