If the front drum is drilled for quicker release of the brake (most area) than you need to plug the factory vent and drill and tap the rear case for a vent. Most (I beleive) run a GM style vent but others (my self included) have had trans fluid leaking from the vent and that is when the hose up to a catch can is a good idea. Run the hose into the bottom of the can so that the fluid will drain back into the trans and you won't have to keep adding fluid.