u-joints?

I just changed my u-joints in my 88 lx. When I drive the car it feels like the car is getting tight and then starts the shake. No really bad but you can feel it more at about 55 mph or so. I have made sure that the bolts are tight and that all the clips are in. I don't know what it could be. I did mark the driveshaft before I took it off so that way I would put back the I took it off. Any ideas?

Were the Ujoints lubricated? Sounds dumb but I had the ujoints replaced on my 87ranger and a few weeks later one went bad because the shop didn't lubracate it. It will get worse as time goes on if this is the case.

I didn't think about that. I thought that what was in there was enough. I also was thinking that I need more trans fluid, I had some come out of the end of the trans when I took the Driveshaft out. I'm also going to make sure that all the bolts and clips are in there right.