I missed a shift, big time! Now my driveshaft has side to side play on the end coming out of the transmission, what could be wrong?
Bearings?

 

the slip yoke should not have any play in it, just go in and slide out with ease. if their is wobble then either the brass bushing is worn or the slip yoke is badly gulled. you must pull out the driveshaft and inspect both a.s.a.p. or you could cause an accident.