As it happens, I have an OEM pivot pin sitting on my desk in front of me as I type this reply. It came from the Monster Case 446 that Joe Hemi parted out a few years back an it is in like-new condition. Overall, it measures four inches but the distance between the circlip on one end and the hole in the other end where the locking pin slides through is about 3 1/8 inches. It is 1 1/2" in diameter and is likely nothing more than standard cold-rolled steel rod.
The pin I have is cross-drilled in the mid-point to allow grease to lube the pivot point and there is a grease Zerk screwed into the front face of the pin. I see no accommodation for greasing the pivot area with this over-priced pin kit from Dan Haas. Therefore, it appears that you would have to drill the axle and then tap it so a Zerk could be screwed in.
I have never considered the pivot pin to be a burning problem in search of a solution because it takes many, many years of abuse before it becomes necessary for replacement. The most common issue is that owners fail to keep the tractor properly greased. The second issue is that owners don't watch where they are driving and ram one of the front wheels into something that does not move. That is what causes the crossmember plates to get bent but it also causes the axle itself to bend or twist. While this design does offer some additional support, I don't see it as being the panacea that is touted in the hype. YMMV.