Found my issue
Decided to degree the rear u joint on the rear driveshaft. After cleaning it I found metal shards (remains of the bearing retainer) twisted up in there. Even though the joint has no play in it when pulling on it, visual inspection showed otherwise.
Fortunately for me I just happen to have a genuine oem Isuzu u joint in my garage that I had ordered about 10 years ago. Now I just need to swap it out this weekend.