Actually the axle was designed by Napco, built by Dana exclusively for IH, per Dana tech support. It's rated at 9,000lb. The knuckle ball is larger than a Dana 70 and no parts from a Dana 70 will fit it. Surprisingly parts are still available for it from both Navistar (using IH part numbers) and Dana (using Dana part numbers). However the parts (seals, felts, bearings etc) cost almost exactly 3 times more from Navistar. I know because I bought all the parts (seals, gaskets, new drain plug etc) everything I thought I might need in rebuilding it and bringing it up to my standards. However those parts don't go with it because they also fit my Loadstar's parts truck axle.
The pumpkin is the same as a IH RA-30 and has a ratio of 7.17. No locker. It has Dayton spoke wheel hubs and locking part-time hubs. It's too wide to work on a 60-78 Loadstar, only an S-Series Loadstar or other wide truck from the very late 70's onward. It's either a FA-64 or FA-78 with a corresponding IH code of either 02064 or 02078. I have not been able to find any difference between the two in the IH parts books. It tips the scales, with hubs and brakes attached but no wheels, at 1260 lbs. It was made for 3 in. wide leaf springs but I'm sure any width spring will work ok on it. What else would you like to know about it?
Thanks.