The Mag risers started in about '71 I think. Using the first digit in the numbeer to date Bear bow ended in '69. Somebody like Bowdoc or Al reader might be able to help you, but I can't.
I think I married her mother in 1968. Got my freedom in 1973. She was COLD, but she grew to be "UGLY" too. She would have been about an "A" riser, but #3 limbs. Long and lankey.