It didnt seem loose, even though the input flange spins very easily, but smooth with no play. A swapped in another borrowed differential and still had vibrations.

 

Yup, retorqued everything, aligned and corner balanced. Still tracks and drives straight but wouldn't hurt to take it in for a checkup.

Been considering those subframe collars though.

 

No wheel spacers. Tires are fairly new. I've rotated them every wich way possible, left right, front back (255 square setup) with no change. Even put hubcentric rings in to eliminate possible misalignment.

I have put stock wheels just on the rear and it has lessened the vibration considerably. Still not convinced it's the wheels though since rotation has no effect.

Thanks eveyone!