Stupid moss/TD question: (e) and (c)?

[Adam Arabian <arabian@allegronet.com>]

I'm sure this should be obvious to me, but I just started looking at the
moss catalog to get replacement parts for my 52 TD, and I'm a bit
confused about the numbering system.  This is my assumption and I was
wondering if someone could back me up on it or correct me:
if it says
TD from (c)20942
Is that from chassis number 20942 and if it says
TD from (e)15371
is that the engine casting number?  or what?

The moss catalog doesnt seem to specify, so I presume its one of those
things that I SHOULD know - but if theres one thing the process of
rebuilding this car has taught me, its that there are a lot of things I
SHOULD know that I dont....

Thanks,
Adam Arabian