Cat D6C Final drive question

While looking for a D4 I have ran across a 1971 D6C #10K7226 that has final drive problems. The face of the smaller pinion gears teeth have been hot and are flaking.
The medium size pinion gear has teeth that have had the corners broken off. And there are bearings that have been hot and are gone. The bull gear seems fine as well as the case and cover will be usable, though skint up.
The fellow I have talked to explained that he has looked several places and is unable to find these 2 gears. He spoke of the C series tractor being hard to find parts for.
I am looking for information on availability of these gears, bearings, and maybe an idea of price for these if available.
As best that i can make out. The small gear has a # 53192 on the end of the shaft. The medium is # 1R1898. The "R" is hard to make out but I believe it is an R.
I have pictures but am unable to get posted. If anyone with knowledge of these tractors is interested in seeing them I can send.
I appreciate any information. Thank You.

The pinion is 5s192 and the gear pinion is 8s1064

Here's a good source for parts
http://www.machinerytrader.com/listings/dismantledsearch.aspx?ETID=3&Manu=CATERPILLAR&Mdltxt=D6C&mdlx=exact&GUID=B5ECD34C9B834ADBA3EBC484209773B0
and
http://www.catused.com

gemdozer, I have looked again at the gear pictures, and other than the "R" being hard to read, the 1 1898 are pretty clear. It is a 2 in 1 gear for lack of a better discription. A larger diameter, approxamately 12" and a smaller at around 6" in the same casting. This I believe drives the bull gear.
Thanks

Thank you alan627b. I'll check these places.
gemdozer, thank you for the S in the 5s192

Yohan: I have some of these parts available. Email me directly for more information. [email protected]. Steve

Thanks Cat-Iron. I will wait to see.
Do you remember cost to change these out?