74 is when the shock absorbing bumpers were introduced. The brackets on 74 and newer are actually cylindrical shock absorbers. The 74 and newer fenders have a triangular shaped hole for the brackets and rubber seals.
I imagine you could do some cutting and welding and get an older version to work, esp. if you have a used set for a pattern.
Good luck
---
Our VWs Over Memphis (all VW) Car Show is the 2nd Saturday in October. Check main web site, events for updates. http://www.midsouthvw.com