Righto sounds good Stephen. Machinerytrader is showing pinions available so I should be good there.
While I have you, what would your thoughts be on whether a short track frame could be extended (maybe add a roller) the requisite six inches for a "long" track frame? The adjuster bolt would need to be longer and I wonder if the blade ram mount holes would be in the same position? Maybe that's a workaround to the lack of long track frames.

Thanks Stephen, the rear spring perch is definitely the six inches forward on the long frame vs. the short frame, so presumably the adjuster parts are the same as you mentioned. I'm beginning to think that it wouldn't be terribly hard to make a new set using flat / straight cut pieces rather than trying to make the bends like Cat did. I'd reuse the pivot shaft tube and replace everything else

Question for the enlightened - the serviceman's manual says to tap the final driven gear hub while tightening the nut when refitting it to the shaft. That fitment is very similar to the sprocket in that it has a similarly sized splined arrangement, and yet the sprocket is to be installed with 15 tons. When I removed this gear, the nut and gear were essentially loose on the shaft - seems like I should reinstall with at least, say 5-8 tons - what do you all think? The hub on the gear is not as thick as that on the sprocket so it would take a lower tonnage, but I'm surprised that the manual says just to tap while tightening (although it also says that doing so will seat the gear securely on the shaft)

HFDZL - I didn't think to check there in the front of the book but when I did, mine (Form 30441) says 20t so it's different again
Jeff - just splines like the sprocket side but a slightly smaller diameter
Dan - interesting. Given that though, would you recommend the tap-and-turn technique (after all, it is what the manual states) or put it in the press to "something" tons?

I have a hollow ram and a pressure gauge pump so I'd just need to make up an adaptor. I have an adaptor for the sprocket so I'll make one for the driven gear. By the time I'm done with this unit, I will have every adaptor for every pressing requirement : )
Given that I need to also refurbish the other side of the tractor, having all this equipment should make that job go faster / easier