Reply to "Driveline vibration after lowering car?"

Do you belong to a Pantera club or know anyone with spare parts? Borrowing a pair of halfshafts or even wheels & tires for debugging has been done before among club members. There are members of the PONE (Panteras of the North East) Chapter of POCA up your way. I'd hate to see you spend time and stomach lining on all this with halfshafts, then find that one wheel has dropped a balance weight.

To set your mind at ease and eliminate the halfshaft assemblies as the actual cause of your vibration, take/ship both halfshafts to a shop such as Driveline Specialists and have them expertly inspected and spin-balanced. Worn yokes sometimes have oversized holes for the u-joint ends to press in, resulting in a loose fit. I've seen yokes in which u-joint ends literally fell thru or had cracks.

If a very close examination of the u-joints, yokes etc show actual shiny spots from metal-to-metal contact, perhaps some extended-range u-joint assemblies would help. The driveshaft shop will know if that's even possible or necessary.

For the small amount you say you have lowered your car, there should have been NO effect except the need for a 4-wheel realignment. You could also easily return the chassis to whatever the non-vibration stock height was, and see if the vibration is still there or if it vanishes.