I didn't worry about "degrees" of anything, just found one the correct length and ran it. In my case - Harper's bracket, alternator bought on ebay - I used a 15295 belt. From ThisOldTractor: Dayco 15295 (metric part number 11A0750). 30.1 inch outside circumference, 29.5 inch effective length, 0.44 inch wide, 36°