I have an 84 Camaro, 305, with wide 235 tires and when you get on the gas from a standing start, there's a loud thump coming out of the passenger side rear, like the tire hit a bump in the road. Automatic trans, it winds up snd then makes a loud thump noise as it shifts up. I just changed the U joints and the transmission mount looks ok. It has the trailing arm type rear suspension. Any ideas appreciated.