After a bit of digging and a few phone calls I found em!
The linkage grommets are pt#
HRN-23 (1948-1966 Shift rod grommet, with metal lining) at
American Classic *Note: They don't come up in a normal search for transmission or shifter parts like the box arm bushings do.
The
47-53 requires six of them and the
54-55 gets four.
For those rebuilding the whole box, you'll need these parts too.
CB803 (1947-1959) Column shift bellows
SLRB4 (1947-1959) Shift lever rubber bushing pair