put in 8 3/4, now have vibration

Also, I am not certain, but it looks like your yoke is made for the big joint. Take the joint out from the driveshaft and try fitting the larger end into the yoke. If it fits well, you should use a standard 7290 (big) joint. I think that is all it could be as the 1350 stuff uses U-bolts instead of straps.