More research on the net including other truck forums: the consensus is that the only traction aide available for the Eaton HO52/72 axle as used in Chevy and GMC trucks from 47-72 was/is the NoSpin/Detroit Locker. Available as a factory option from 60(?) to 72 and in the aftermarket. Eaton owns the Detroit Locker brand now and ones for the HO axle are no longer manufactured. There's lots of discussion about using a Locker made for the GM 14-bolt, as mentioned above, but the 30-spline axles have to be modified...
Oh, well. Thanks for the comments.
