I have a '68 Camaro, and I just dropped in a new engine & tranny a few monthes ago. When I got the car, it had no engine, and I was told that the heater core leaked. I had the heater bi-passed, but finally got sick of freezing, and hooked it up today. It leaked, but a little radiator stop-leak fixed it. I would like to change the core anyway. How difficult is this to do? Will I have to remove the fender, or inner wheel-well? Any advice will be appreciated.