Its from Yamaha's line of composite racquets that were sold in the late 70's. They were made in the same manner as snow skis were then (aluminum skin with fiberglass and plastic cores) and targeted at the Head Ashe Comp. The 124 was at the low end of the line. There was also a YCR-126 that looks like yours but is red and white.
I have a YCR-126. Weighs 13.3 oz and is balanced 6.5 HL. Very, very flexible.
You see them on the big auction site once in awhile. Typically go for $10-15.
-k-