What should I be looking out for in the event they did not change the bearing race and used the old style bearing? Right now all I have is a very faint (almost nonexistant) whine and a decel vibration at around 70-75 mph or 2200-2400 RPM's that was not there with the 2.73's. Installer chalked all that up to a weak factory driveshaft and the way the gears are made. It hasn't been a real big issue anymore tbh
If you have a manual transmission then the deceleration vibration is normal and due to the dual mass flywheel.
If not then it could be the gear or a driveshaft issue like the companion flange did not get fully seated when the driveshaft was bolted back up.
As to what to look for, the noise and a bad wear pattern on the gear teeth.
Have you asked your gear installer about it yet?