We bottomed the slip yoke and then came out to 3/4in and had the driveshaft built to that! I chatted with Colin and he said anywhere from 1/2 to 1-1/4in is acceptable. 3/4in being ideal. So it's right in spec.I chased a vibration for a long time. I finally had a drive shaft made that was a little longer and solved the problem. How much slack do you have in the slip joint after you install the universal into the rear end yoke. It should not be any more than about 3/4". Just something else to check when all else fails. My driveline had been balanced and had new universals also.