slip yoke play

[WSSix]

I swear I've asked this question before but I can't find the thread. Anyway, in my effort to hunt down what's causing my high speed vibration, I'm looking at the slip yoke and output shaft of the transmission for excessive play. I get some vertical play by just pushing the driveshaft up right at the front u-joint. I can wiggle, for lack of a better term, the output shaft of the transmission when the driveshaft is not in place. Is there any play in the output shaft on a T56? I'm looking at replacing the output shaft bushing since it's got 180k miles on it but wasn't sure if I should be looking further in on the transmission, too.

Eventually, I'll rebuild the transmission, but at this time, I'm just trying to rule out play in this area as the culprit for my vibration issues.

Thanks!