The plan to rebuild the Grizzly DF-1237G took a brief turn when a Clausing Colchester in good condition showed up locally on CL. Alas, it was apparently already sold by the time I saw it, as the seller did not return my message. A Hardinge HLV-H also showed up, and while I drooled over its specs, the $12,000 asking price is simply a bridge too far. Even if it wasn't, the reality is that I don't make anything requires such precision. Oh well, it's hard to not always want "the best".
Back to my lathe, replacement oil seals are onhand, so the teardown will proceed - and I'll stop looking at CL. I changed my thinking regarding replacing the chuck with a D1-4 chuck, because it'll make the process far easier. The new plan is to replace the existing chuck with either a Buck or Bison "Tru Adjust", using the existing backplate. This gets around having to fabricate a new backplate in order to gain what's probably a questionable amount of precision. The only question now is how much the backplate might have to be modified.
Speaking of the factory chuck, does anyone know what came with the Grizzly DF-1237G as-delivered? The reason I ask is that when I got it, it had an 8-inch 3-jaw on it. I kinda doubt that's normal. The chuck has no markings, so I don't know what brand it is, and the engineer in me has to ask, "How do I know that it's not already a high quality name brand chuck?" Well, I don't, but I think if it was, they'd proudly display their name or stamp on it. I also think that most people wouldn't make that change, but since I'm considering it, who knows.
Regarding the backplate, I actually have three! One for the 3-jaw, one for the 4-jaw, and another more generic one with a bunch of slots in it (which I need to confirm if it threads onto the spindle. I removed the 4-jaw backplate to see what it looks like. It has an 80mm bore that's a press fit into the chuck, but what's odd is just how rough the backplate threads are. It's as if it was threaded, then sandblasted with 1/8" sand, because the threads are very rough, like 60-grit sandpaper. Makes me wonder what the history of this backplate is. Anyway, this backplate is maybe 6" in diameter, with four mounting holes at mid-radius. The 3-jay backplate is 8" and has 3 mounting holes out near the edge. The third backplate with the slots is at least that big, maybe even larger.
Anyway, the whole chuck thing is for later, because in order to get there, the lathe has to be rebuilt first. Given some of the comments, getting the bearings out of the head could be difficult, and hopefully I don't ruin them or anything else.
I'm considering doing a YouTube series of the rebuild. I doubt there are very many people considering rebuilding one of these, but producing the videos would be good experience for me since I plan to do others (drawbar and car-related).