Okay so here's the problem: the front end on my 70 Duster refuses to stay aligned. A few months back we had to pull the motor, so we yanked the front end like we normally do (lift the body up and over the engine). When we put everything back together and took her down to get aligned, it wouldnt work. We didnt mess with the tie rods, nothing, just disconnected at the upper control arms. The alignment shop gets the front end sitting at the height i want it to be, then aligns it just fine. But when i drive it and get on her, the front end comes out of alignment and raises anywhere from an inch to two and a half inches. Could this be weak torsion bars? They aligned it and drove it and re-aligned the front end over 7 times today and it still will not stay put! (the torsion bars are the original /6 ones by the way)

Thanks guys