Tony, I'd be leaning more towards it being a tire issue. I've twisted driveshafts in the past and only had a vibration through 1st and 2nd gear...not noticeable anywhere else. Once in high gear, it smoothed right out. Had this happen twice.
Last year I had a slight vibration in 2nd gear only...turned out to be wear in the U joints. New U joints and it's smooth as silk again.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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