question of value for rear diff experts

got a little surprise this past week. purchased what were supposed to be a new unused 3.55 richmond set for a 12 bolt chevy. when I opened the box the gearset appears to be unused, but with 1967 dated GM 3.55 gears. part numbers pinion:3853008 dated 8/67 11-39-GM, and ring : GM 3853010 11:39 dated 9/67. Now I know what a new rich gearset goes for, but these appear to be never used NOS GM 3.55's. I still have every intention of installing them in my velle after I come up with a posi for it, but am just a little curious what they might be worth. Any input would be appreciated, and thanks in advance Jason.