Topic: 67 disc brake calipers

[67gta289]

Just disassembled the disc brake calipers and there is a significant difference between the two.  In fact, one of the two halves has an above surface sheet metal type retaining ring for the dust boot, the other half and other side are below the surface.  What is the proper way to identify the correct calipers for a 67?

Some pics below.
 
Thanks, John

[midlife]

I believe the housing with the steel ring on the outside is a 1966 style.  The dust boots for the pistons differ between 1966 and 1967 and cannot be mixed.