Ford Rear End

Can some one decode this rear end tag for me. WDM-A1 OBB 3.50 8.7 318A I am trying to find new rear brake Drums Auto parts store can't match up old drums. Help Please

THE WDM-A1 Could be WDM-AD or WDM-AO the tag is bent in the AD Or AO location

 

8.7 indicates it's an 8.75" rear. They're different than the 8.8s in a few ways (axle bearings, seals, etc..) as I found out myself. The gear ratio is the 3.5. Probably from a Monarch or Granada, or something like it, late '70s or early '80s.
I tried to get a full decode on my tag but Ford up here gave me the "our computers don't go back that far" story .

Flatman

 

Part number off a backing plate would be more helpful. It does have a a 3.50 final drive though! BTW introduce yourself or pay the price. Stu

 

backing plate #'s are Bendix 316279-R 316278-L

 

hollander shows

wdm-ad to be a 63 to 72 ford f-100 3.50 9" rear

wdm-a1 or wdm-ao are not listed.

 

@Flat-TOP-BOB would 63 to 72 ford F-100 be 5 x 5.5 stud pattern? This creation (for want of a better word) is 5 x 4.5 pattern.

 

Ford pickups for about 80 years or so starting in 1928, except for '36-'39, are 5 on 5.5.

 

This is the “creation”
https://www.jalopyjournal.com/forum/posts/15313725/