My favourite D6C model is a 69J, not sure what the equivalent serial number is in a US built machine. 140hp PS f/w straight blade and Standen Rippers. Very durable tractors, for me the pick of the D6C tractors, right at the end of production of the C series.
Happened across his 76A on craigslist, might be worth a look https://slo.craigslist.org/hvo/d/cat-d6-76a-series/6488667183.html
Late 10K is a nice tractor.
17A is a nice machine with the best turbo engine sound on the planet. But parts are hard to get. Cable blade is clunky and hydraulic versions are slow and the seat is terrible to sit on.
Most of them in Aus have been totally trashed unfortunately, with large numbers used /abused in forestry operations. Rear end will crack around the transmission top from winching or rippers if fitted and pilot motor has the usual mystical issues mostly related to magneto spark dissappearing when needed or rust in the petrol tank.
However the 17A will become collectable I think....I hope....
The 10K series with the powershift are the best (IMO) of the D6C's but of the 10k's I'm not sure if simply newer is better but finding a 10K with real good U/C and some bells and whistles will put you in the $25k+ range from what I've been seeing.
A D6C direct drive (like 74A) will be much more affordable because they are less desirable (unless you're a farmer).
https://sacramento.craigslist.org/hvo/d/catipillar-d6c-17r-special-app/6510202049.html
Jordan
My 76A is power shift and one he'll of a machine. I wouldn't consider them undesirable. My other contractor friend that I pair up with on big jobs runs 10ks. I have spent hundreds of hours on both and my older 76a pushes just as hard as a 10k any day.
A D6C 10K series s/n 7953-up with the 3306 would be my preference. Lots of units built and generous parts availability.
The 10K series with the powershift are the best (IMO) of the D6C's but of the 10k's I'm not sure if simply newer is better but finding a 10K with real good U/C and some bells and whistles will put you in the $25k+ range from what I've been seeing.
A D6C direct drive (like 74A) will be much more affordable because they are less desirable (unless you're a farmer).
https://sacramento.craigslist.org/hvo/d/catipillar-d6c-17r-special-app/6510202049.html
Jordan
I found this to be true when looking for a D6C , either they were junk or $25 to 35K for a dozer/ripper. I settled for a D4D dozer/ripper it will do what I need just takes longer ( more fun) LOL