I think i've the parts numbers for these mouldings (but sorry i don't have any spare ..) : 1810 854 and 1810 855 : folding top belt outside finish moulding.
Yes, it's me who send to Henry some pics for the ends of this mouldings. Pics of these ends were sent me by another '57 Imperial owner because i haven't them on my car.
When searching for references i find that the two inside belt mouldings are not referenced in the 2 parts manuals i have !!! One (the higher, which is attached with the outside molding and studs) is in the Canadian manual (1810 852 and 853) but not in the 55-58 US manual. The lower belt moulding (1810 104 and 105 ) is in the US manual but not in the Canadian !! I'm looking for the 1810 106 which is the cap at the midle (lost during the 7 years or maybe before i bought the car ..) of the two lower belt mouldings ...