Shaking Between 40-60MPH while Throttling

Ok, so I've had a problem ever since I had my tires replaced by my local tire dealer. Along with the new tires, I forked over the money for the alignment as well (for good measure...); however, ever since then, I have had a problem with my car shaking when I throttle through 40-60MPH.

It shakes really bad between those speeds; however, when I take my foot off the gas, it seems to go away. I have another GP so I swapped the wheels off that one and threw it on the troubled GP and it didn't change a thing. It's a GTP, but it doesn't seem to change when the s/c kicks in so I think I can rule that out....(hopefully!)...

What do you think the problem is? Half Shaft bent? Alignment messed up?

Let me know what you think. Thanks!

Check your lug nuts i had the same exact problem if not that change to a whoe other set of tires and rims and check... or take them back to the dealer and tell them the prob.

Like I said, I took my bad wheels (rims and tires) off my troubled GP and put on ones I know are good from another GP. Didn't fix the problem...



any other ideas?

Input shaft.

-Swash