9 1/4" Axle Swap?

Like I posted to someone else, it might be easiest to unbolt the springs, brake line, e-brake cables, and shocks from the car and take the whole assembly as one unit. That way you have everything you need, and it's a heck of a lot easier than removing the u-bolts. If the springs are better than yours, bonus.

If the donor car has the same transmission as yours get the driveshaft, too. Your current shaft will be too long. If the transmission is different, you can have yours shortened, or have a custom shaft made.

I'm not sure what car you're working on, but don't forget that any 8.25 axle that you find will have the big-bolt pattern, so your wheels may not fit.