These are new uni. joints. Caps are the same size, I will attempted to clean the seats on the yoke.
Are the straps normall strong enought to draw the caps completly into the seat of the yoke?
If you got the U joint into the driveshaft itself and got the clips in then it should be the correct joint. The caps against the yoke is an interference fit so they might go in a little hard but it shouldn't be to tight. Clean the crusty stuff out of the seat of the yoke and like Lance said draw them in by alternating around on the cap bolts.