Correct me if I'm wrong , John, but if the old center was in the later housing with the later axles, I'd say you could use that center in any housing. If I understand correctly, the axle end play must have been sloppy for years. But the driver didn't notice? Couldn't you adjust the adjuster in more on the one side to take up the difference? That's an 1/8" each side, right. If not, couldn't you use 2 right side axles to take up the adjustment? Just wondering. Doesn't really matter since most people won't want a pre 64 open in a 65 and up housing. They want sure grip!