Help with '55 Crown Vic "top of rear door seal" Early/Late?

[RocketsGarage]

Trying to sort out the weather stipping on the '55 project and found a discrepancy. Seems like there was an early & late weather stripping for the back top of the door? I'm missing the cast retainer thing for the driver side door and can't seem to find install instructions anywhere? Seems like maybe this was done away with it late '55 & '56? Would like some advice and guidance from those who've dealt with this??? Thanks!