Any driveshaft place can build you one, look on line and they should have a form you fill out with the dimensions they ask for. If I remember correctly I used DTS driveline specialist here in Metro Detroit.
http://www.drivetrainspecialists.com/
If your old driveshaft is in good shape and too long it can be shortened. You should have some place local that can build you one as well out of your old one. I did not do that as I sold my old transmission and drive shaft together.
Good luck.