Where the rear pinion bearings changed? Maybe that front pinion bearing is bad, nut tight? That might be the place to check since the "noise" came after the gear change. I thought I read you replaced it all at the same time.
Also since you had to change front slip yoke, is it bent? Have to watch it turn running in gear. Only way to check the driveshaft for harmonics is to try another one.
No, nothing was changed when the gears were changed to 3.91 recently. Everything was replaced in the rear a year prior when the sure grip unit was installed with the 3.21 gears previously, so nothing was touched this past time around.
The front slip yoke was sourced and put on the front of the driveshaft back when the 4 speed was put in early last year. Nothing appears bent and it all functioned without issue with the 4 speed/3.21 combom before going to the 3.91 gears.
My dad is checking for engagement of the driveshaft into the trans today while I am at work, making sure that the driveshaft isn’t backed out more than .750-1.000” after pushing it in as far as it will go. Will report those results later.
