8 1/4 Into A 65 Barracuda

Get the u-bolts and shock plates along with the rear end as they are different also. You'll have to use your old e-brake cables as the '73's are different length. As slantscamp said, you'll have to shorten your driveshaft. Naturally, you'll have to get wheels with the 4 1/2" bolt pattern and the fun of carrying two spares unless you're going to convert the front end too!
Thanks, Mark