boylee,

TJ probably indicated 4100 in 1950 because:
UJ indicated 4100 in 1951, and
VJ indicated 4100 in 1952

14TJ-C 1173
14 = Baltimore, MD assembly plant
T = probably indicates 1950?
J = probably indicates 4100
C = March
1173 - 173rd truck off the assembly line (seems a small number).

Maybe someone else can confirm, or correct, or clarify (or speculate)?