Found this:
http://shootersforum.com/showthread.htm?t=39615

USRAC Model 70 serial numbers are a bit of a mystery - nothing official ever published. With the push feed guns USRAC continued the post-64 WRA serial number sequence. When they introduced the M70 Classic in the early 1990's they started over at G1 (pre-64 rifles didn't have the G prefix) - how far they went each year and where they stopped I don't know.


Bruce