If it is an Upstate Replicars Daytona it is a Jaguar rear end. It should not be too difficult to get spare parts.
The Daytona from Upstate is now produced by Lesher Motorsports. They should be able to help you.
http://www.leshermotorsports.com/index.html
George Petrus at
Accurate Machine Products
20417 Earl St., Torrance, CA 90503
May also be able to help you. However, I cannot find his site anymore.