Mine came with a tag reading J-3057, which in a Kent-Moore tool company part number.
It is listed in the GMC Maintenance Manual as "Steering Knuckle Bushing Reamer" for 15x and 25x (3/4 and 1 ton) models.


'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.