Looking at options for u-joints on rockauto.com:
https://www.rockauto.com/en/catalog/chevrolet,1997,tahoe,5.7l+v8,1061367,drivetrain,universal+joint,2392
I think I should go with either of these:
https://www.rockauto.com/en/moreinfo.php?pk=387875&cc=1061367&jsn=535...