LB,
That fleabay Bluegrass is a Thorsen - there's been at least three different sources for Bluegrass ratchets. The earliest I have is a New Britain Fors patent head and a later Kilness patent round head. Wright also produced them for a period, and I'm assuming Thorsen was likely the last source. At least that would make sense to me, since store brands seem to cheapen over time.
My guess would be that New Britain sourced the sockets/drive tools until NB went down the crapper (or until shortly before), then the quality level was continued (or maybe even improved slightly) with Wright as a source until Belknap started faltering, so they switched to Thorsen to cut costs until the end. Strictly my uneducated guess. The few wrenches I have are from Barcalo, but I vaguely remember seeing some from another source - can't remember who.