Driveshaft looks maybe a hair short, but, I don't think it's enough to cause a vibration. Your angle off the trans doesn't look good to me though. You might try adding some spacers under the transmission mount to raise the tailshaft giving it more of an angle and give it another test drive to see if that changes anything. If it cures the problem, you'll need to make a more permanent modification, but, the shims will work for test purposes. Adding the shims will make the driveshaft even shorter, so, you may end up having to do both, including changing the rear pinion angle. Depending on how thick your test spacers are, it may change your shift linkage adjustment, so, you may have to readjust that too.
