I am ready to now bet on the 3600 and 3800 engine rear supports being different for H-M equipped 1954 trucks (I do not gamble - gamblers can lose):
Here are the LH and RH
engine support brackets that get riveted to the side rails on 1954 H-M trucks; and, they get bolted to the "center" support member under the engine rear mounts. It also lists the separate H-M "center" support member (used on 3100, 3600, and 3800 H-M trucks).
