[Gearhead999]

I don't understand your term..."shifting". As FatOeknee stated it could be wheel hop, which is rear spring issues.

Or if your cruising down the road 35 mph to 55 or so mph. Then you plant you foot in it and the rear "shifts", does it clunk?? car change lanes?? vere to one side or another?? bounce??

A little more info would help.