So, I have a 78 Malibu I just picked up two weeks ago. Basically stock 350 with a 350 trans and stock rear. I found a 7.5 inch 10 bolt posi rear with 3.73 gears so I bought it and last night put it in. Went out for a ride, it runs awesome but I went to do a burnout with the car (at the request of my 15 year old lol) and man, I thought it was gonna shake the whole car apart I had wheel hop really bad. Now it didnt do this when I had the open rear in the car. The car sits up slightly in the back, the guy I bought it from said he was going for the old school look and he installed I think it was springs from a wagon. Could this be my issue? I did it once more while I had my son watch and he said the tires looked like they were bouncing. Like I said, going down the road normally I have no issues. Not even when I pull out hard. Just when doing a burnout. Any help would be greatly appreciated. Thanks in advance