Odds are, the powertrain or rear suspension is not firmly bolted down. Remember when you're under there trying to shift things, that the powertrain weighs almost 700 lbs and you ain't gonna affect it much without serious pry-bars. If you can, remind me NEVER to shake your hand! The bolts going from the motormounts to the block typically break as the rubber vibration separators in the mounts age & collapse (or disintegrate), bending the bolts until they snap. A second possibility is, rust or unrepaired frame damage has loosened (or removed) the crossmember under the oil pan or cracked the rear subframe, allowing the lower rear a-arms to flex the whole suspension under power. One young owner with NO crossmember in his Pantera found he could pass trucks on the Interstate simply by downshifting & hammering the throttle; the car would change lanes with no steering inputs needed.... None of these possibilities are trivial and I may not have guessed right, but I urge you to continue looking as something is seriously wrong especially in a car with the capabilities of the DeTomaso Pantera.. A third poosibi;ity is a badly worn rear stub axle in one or both rear usrights. The axles are soft steel and were slightly undersized as new for the bearings. So the hard bearing races wear the axle, allowing the rear wheel(s) to wobble. This can be checked by 2 people. Remove the fiberglas trunk and one person stand looking sharply at the rear hafshaft on one side. A second person then throws their haunch into the fender on one side (but don't dent the fender!). If the rear wheel bearings are bad, the half-shaft will arch sharply upward NOT in the area of the u-joints. Chrome-molt-steel stub axles, properly machined for the bearings, are available from all the vendors (including the owners of this page) and will fix this problem.for any conceivable use, even pro racing. But its not an easy repair at home.
