My d6 has the earlier impeller with no ceramic wear piece and has around a 32nd of wear. Do you think i can get away with machining the impeller face down and replacing the bellows assembly?

Thanks!

Don't see why not, so long as your still in range of the bellows compression.

Update
I ordered a new shaft and impeller, both CTP aftermarket parts. The replacement for the shaft 7f2676 was 2P2239 and the replacement for the impeller 4f5995 was 1m7571. As far as I got I couldn't find the original parts online and these new ones were listed as interchangeable online. Ended up they are close but not exact.

The new shaft has a few insignificant changes(threaded hole instead of a post to hold the impeller down, no key slot) and one significant change being that the shaft where the impeller seats has a slightly bigger taper. Seems you would have to bore the impeller to get it to seat properly.

The new impeller has a slightly shorter length than the original, making it sit further from the bellows seal. I thought to bore it out a bit to make it sit further on the shaft but the impeller fins also sit closer to the wear surface than the original. I think I would have to shorten the fins along with boring it out to get it to fit properly.

In the end I used the old shaft which only had wear on the grease seal surface and the old Impeller which I faced and bored out to make sit further down on the shaft.

This was on my D6 9U11838. Took me awhile to figure it all out so hopefully its useful to someone
2p2239 100$ Ebay 300$ CAT
1m7571 60$ Ebay 250$ CAT

Keep us posted on your progress, and maybe some pics when you have the old gal working again, please.
NickyWalnuts: Do you have any pointers for your fellow nut farmer? He is a young pup, and not as old and wise as you...(LOL)
I wonder if the differences are due to any serial number splits/upgrades for parts, like other machines?
TulareNut: It has been nice seeing you bring many of your tractors back to life. Keep up the good work. JM