I found an old 53 half ton frame (even an existing working truck will do) and I made a cardboard template of the mounting holes from the inside of the frame channel.
I used the snubber on the kick up as a center point. I then transferred the cardboard to a piece of plexiglass and drilled holes in it where the bolts/rivets were on the frame. I cannot say it is exactly 100% spot-on but am very close to the original. I know that some of the after market companies sell conversion kits and include a template. Don't know if you could just buy the template by itself.
I have yet to complete this modification but when time comes I will put the plex in the channel and drill the holes. I have done a few 'dry runs' already. It can get snug on one side with wires and tubing being there but it will work.
I plan to use Grade 8 bolts and am thinking the shock number for the 53 will work.
The brackets I used came from that old 53.


1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice