8 1/4 rear for 68 dart

Looking to replace my 7.25 rear with something a bit stronger. Sure grip preferred. I'm located in south eastern PA. Any help is appreciated.

Not Mine, the whole 9 yards, springs driveshaft hubs the works

1973 74 75 76 Mopar A-body Dart Duster 8.25 8 ¼ Rear End Axle Assy w/ Sure-Grip
1973 74 75 76 Mopar A-body Dart Duster 8.25 8 ¼ Rear End Axle Assy w/ Sure-Grip | eBay