Make sure there isn't any large wiggle in the front drive gear at the splined end. Check to be sure the snout that the throwout bearing sits on is not cracked. Pull the top and check to make sure there are no large metal pieces or chipped gear teeth inside and that the forks all slide appropriately. Cycle through the gears and make sure the yoke and splined end turn appropriately. And probably just replace the seal at the yoke end just because.
Drain the fluid and as long as there are no tell-tale signs of trouble, re fill and reuse her.
Those transmissions are tough as nails.
Jeff
