Look for a 2-letter stamp near the thumb loop knot
First Letter: J=1976, K=1977, A=1978, B=1979, C=1980, D=1981, E=1982, F=1983, G=1984, H=1985
Second Letter: Z=JAN, Y=FEB, X= MAR, W=APR, V=MAY, U=JUN, T=JUL, S=AUG, R=SEP, P=OCT, O=NOV
In the photo below "BZ" stands for "1979 JAN"
As...