Does anyone know the alloy used to make the pins for the "G", as in 310G series J.D. backhoes? The pins drill fairly easily with plain HSS bits. If possible, I need to know if there is anything special about the pins. I need to make several.
Specifically? No. Generically, owning an old Ford hoe:
If the holes are bushed or sleeved with a bushing that is easily replaced, a hard pin surface (and new bushings) would be good. If it's a royal pain to redo the holes (no bushings, or you have to weld in and line bore) a softer pin is good, and replace the pins more often. In either case, grease is good.
Practically speaking, I replaced my bucket pin with a hunk of HRS - while not great, it's better than the worn out hunk of crap it replaced, and I could get it locally, cheap, fast. Since there are supposed to be bushings in there (they were gone, I put some in), CRS would be better, and drill rod would be better than that, barring a degree of fuss with case-hardening that's easy on a large scale, and a bother for one-off parts at home (but if you are set up for it and want to bother, go right ahead). However, drill rod would also set off my "...and how many dollars am I putting in, for how much actual benefit over CRS?" response.
I have used both 4140 and 1144 also called stressproof for dozer and backhoe bucket pins. I like stressproof because you can get it dimensioned to close tolerance and it is rated about 100 Ksi without any heat treatment.
I used O-1 on my little loader. The pins are only 1/2" diameter so the bearing pressures are over 2000 PSI, well over when I hit a rock. I drilled them lengthwise to feed grease in from a groove around the center.