I noticed a leak from my rear end shortly after rebuilding the engine and tranny. It is in 66 dart with 225 slant. I did not touch the rear end when doing rebuild. It smells awful and I thnk some of diff fluid is being flung onto exhaust (explains stink).What could it be? How to fix leaking diff? Can it be done with rear bolted up and car jacked up? Oh yea pretty sure rear is seven and a quarter.