There's very little difference in RPM between the older torque tube 4.10 and a 3.90. I don't know if anyone has ever mated up a torque tube axle with a T-5, but it seems like it wouldn't be terribly difficult to accomplish. IMHO, the torque tube rears were usually 4.10, weren't they? Drop me a PM about the 58 GMC axle I've got that's looking for a home. I believe it's a 3.90.
Jerry

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