I have a 1969 Camaro with a 350 trans that has been slow to engage reverse, but now has gotten much worse. It will not engage at all unless you give it a little throttle, ane then it goes into gear very hard. All of the forward gears feel fine and it goes into drive with no delay at all. The only other problem is a leak that slows up after the car has been parked for a month or longer. Is there something to look for in the pan, or is this the early signs of a needed rebuild?