Rotational Vibration?

Hey all, I've been battling a problem for a while. I have a 94 cherokee with I6 and auto. When getting up to 35, there is a slight vibration through out the whole jeep. It doesn't vibrate that bad around 40 to 50 then it gets vibrating again. It happened once before and the T-case grenaded on me. I replaced that along with the rear D-shaft and Ujoints all around. I also replaced all the steering joints (3 tie rod ends and 4 ball joints) but still feel the same vibration since before the grenade. the trans mount still looks good and all else appears to be mounted solidly. What I did notice is that there is some play between the yoke of the rear of the xfer case and that shaft. the output shaft on that doesn't appear to wiggle but there is maybe a milimeter or two of play it feels like on that yoke. I've tried swapping the yoke out to no avail. I'm on pretty tight budget so any suggestions would be greatful. I did a search and the breaks and all else looks fine. Thanks, Dan

any lift? hows the pinion angle on the rear axle?

It's a bone stock xj.

could it be a bent axle? What is the best way to check for that?