Went from an SM420 to a T5, now have a question about pinion angle

[mark '87 930]

So as most of you know, the T5 is almost 12"s longer than the SM420.. so my driveshaft had to be cut for installation of the T5. That said, I'm no geometry teacher, but there's no way the pinion angle is good anymore. I get increasing vibrations. I am pretty certain it's because my angles changed. Would hat make sense? Or am i barking up the wrong tree?

That said, I never went 65-70mph with the old sm420.. so I don't knwo if the vibrations were there beforehand. Could maybe also be my rear diff.