trans vibration?
 

Ok guys I am new to this forum so please excuse me if this topic is an old one. ive searched the internet with a possible cause but no real answer on how to fix or where to get parts.

1st off I have a 1997 ford e-350 van with v-10. I recently went thru the rear end and replaced carrier and pinion bearings. I also replaced u-joints 2x's in an effort to get rid of a nasty vibration from 45-55 mph. pinion, carrier bearings and rear u joint were bad. Now I have a " clunk" when taking off from D or R if I gas it mildly. ( 1 piece drive shaft) I read somewhere about heavy grease on the splines. ive tried greasing splines with no success. I am narrowing down that it may be a bearing or bushing in the tail shaft of the trans. But I know nothing about the inside of a trans so if iam out to lunch I apologize. lol. Has anyone had both these issues and what has had to be done to fix? parts cost etc? Also ive been reading it may have something to do with my torque converter when it goes to full lock up?? Ive changed filter and fluid about 10,000 miles ago but did not know at time about flushing torque converter, so trans fluid is a mix of old and new. but again no real advise on parts to fix or change. Any info would be great help.. Thanks..