I don't know if the 37 torque tube has the same dimensions as the 47-54 where it bolts to the transmission. If it does then what we have done is use the 3/4T driveshaft that is a torque tube on the front half and open on the rear half. You can then use the 55-59 TF 3.90 rear for which you can get 3.38 (or 3.56) gears that are a lot easier to install in the open rear end. The spring perches need modified and a hanger bearing cross member installed but neither is hard to do.

Evan