So how were those washers attached to the shock tower cap usually?
The edge of the thick washer was tack welded in a couple of spots to keep it attached and in place
Also did they use the same shock bolts with Sems in the middle because they were a little hard to get in and the ones that were in were very hard to get out.
Depends on the year and shock used. The thin flat style is found on 65's and 66's with the Koni's. When they switched to the adjustables they went to the standard factory style of SEMS
What was the purpose of the washer anyway?
Strengthen the area of the shock mount and spread the load out slightly. Done on export cars and part of that package - borrowed for the early Shelby's