Axle Tubes are MADE IN THE U S A . They are available in GN 2 1/2" Bearing , Howe 2" Bearing, Mini 5, Wide 5. The Snouts are plugged welded and all welds are low so 4 link bearings will side over and all axle tubes come with a new hub nut, Inner seal for quick change spool, and 6 -3/8 bolts nuts and washers for the side bell.
For the measurement, use the (B) dimension from the inner bearing seat to the end of the tube. There are photos to show you the B dimension if you need to see so you get the correct length of tube .
GN B Dimension for a 60" center Pinion is 21 1/2 Axle is 30 1/2 long
Howe B Dimension for a 60" center Pinion is 22 axle is 32 long
Wide 5 B Dimension for a 60" center Pinion is 21 1/2 Axle is 33 long
Sorry I do not have a Mini 5 chart