The Grand Prix (1963 single piece frame and 1964 -1965 two-piece frame) were riveted in as a single piece pan: floor, seat bottom and seat back. No tabs were used in the Grand Prix as OEM from Rupp.
Spacing varies depending on location. Front axle, side frame rails, jewel pad steel and seat back have their unique spacing.
I have that information, but will have to post that later.
You are not alone in trying to understand the spacing patterns. I had hope to capture the correct spacing pattern at the 2019 REARs TBO. Was disappointed seeing this on this 1963 Grand Prix...
Spacing varies depending on location. Front axle, side frame rails, jewel pad steel and seat back have their unique spacing.
I have that information, but will have to post that later.
You are not alone in trying to understand the spacing patterns. I had hope to capture the correct spacing pattern at the 2019 REARs TBO. Was disappointed seeing this on this 1963 Grand Prix...