68 or 73 is the width of a BB shell. Yours is 73. As long as the thread is the same -BSA it should screw together and work fine. They're just external cups.

I'd be checking other stuff for the rattle. Pieces left over on the bearing cups, tightening the cups enough, spindle length, torqued bolts at the crank, stuff like that

In the days of internal bottom brackets, I once accidentally used a 73 on a 68 bike. I couldn't get it tight and it rattled around until I figured out what I'd done. Had I used a 68 on a 73 bike, the crank and chainrings would have contacted the frame and been unable to spin.