Old thread with helpful discussion from Richard (EV8G).
https://www.fordbarn.com/forum/showthread.php?t=2976&highlight=Reports+Lincoln+brakes+original
"Some of the original Lincoln-Bendix brakes did not have the outer ring, but did
have 3 mysterious "buttons" around the outer backside. Maybe 39-40? The
rings ARE available to be added for those who want them. The new drums have a deep
outer groove that the edge of the brake plate fits into, which helps keep dust/water out.
Otherwise, the new plates are thick stampings, but lack some of the finer detail of the
originals; as with most stuff, the originals are the way to go IF they can be found in decent
(not rusted to hell) condition and $ is no object... since they are usually not cheap!
There are also different versions of original Lincoln-Bendix brake plates and corresponding
hubs/drums, whereas the reproductions, which are often advertised as 39-40 are
ACTUALLY the scarce, one-year-only 1941 (fronts) that are the same offset as ALL rears
39-48 (shallowest design) and which CAN be used with Ford hubs/drums. The original 41's
used Lincoln front hubs (all front hubs are the same 39-48) and the, again one year only,
flattest drums, which results in the narrowest front track BUT cannot use Ford or KH wire
wheels on the flat drums, or the 42-48 "medium" front drums, without a serious spacer on
the flat drums or a half-serious spacer on the medium drums.
The "trickest" Lincoln-Bendix fronts are the actual 39-40, which have the deepest offset
and have the smaller bolt pattern that fits 32-34 and 35/36 spindles. A special
kingpin/bearing kit must be used on these, and must use the Lincoln hubs BUT the new USA drums fit, which solves the problem that most Lincoln front drums that can be found are machined beyond the limit. The new drums are good for 12.090" so they are also thicker than the originals to start with. These provide the narrow front track, but allow the option of using Ford or KH wire wheels, using only the standard Wire Wheel Support Ring to
support the inside of the bolt circle.
Reports on Lincoln brakes vs original - Th... "