Figured I should update the community and if Nothing else the thread incase anybody comes across it in the future and needs the reference. Keep in mind my machine is a 1981 apparently. I ended up getting the large nut off the end of the drive sprocket by using a plumbers wrench with a 4 foot extension. The last gent that put the nut on used red loctite which explains why it didn't want to move. I ended up drilling and tapping the broken chunk of the dog bone shaft then threading in a 5 inch bolt. I then locked my largest pair of vice grips on the head of the bolt and passed a steel bar through the jaws of vice grips. I then grabbed and pulled (imagine grabbing a bull by the horns and yanking) till the broken chunk popped out. The reason it was stuck is that when it broke it also fractured length wise causing it to want to expand and not leave the space. With this out and the nut retaining the drive sprocket off I needed to get the drive sprocket off. I used the largest gear puller I had and it wouldn't budge. Ended up taking it to a farmer with a 30 ton press which took care of it quick. The next challenge was the shaft itself. According to Eaton / Char Lynn documentation these are 4K series drive motor. According to Bobcat they are 19 CID. That's where everything falls apart. The drive shaft I removed was 4.6 inches long requiring it be replaced with 21372-005. The drive shaft that would match a 19 CID motor Is 4.25 inches long and part number 21372-004. In the end I tried 21372-004 but once in hand it was obvious it wouldn't work. I then ordered 21372-005 from a vendor in Edmonton who got it from another vendor in Dallas Texas. This one fit like a glove. I used a seal kit from loaderpartsource, found the rubber seals perfect but found the nylon seals too large so I reused mine. So I don't know what this means. On the one hand these drive motors could come from something else (I don't know the machines full history). On the other hand if they did then what's the odds that they would also be 4K series motors? I called loaderpartsource and asked if they had the drive shaft (gave them the bobcat part number which is discontinued) and they didn't, hence why I went this route. Everything went back together as anyone would expect. Swapped the rear drive chain for the same side while I was in there since it was damaged, followed the trick of connecting the new one to the old one and rotating the tire backwards (while off the ground) to place the new chain on the rear sprocket. A chain breaker made the job easy, and zip ties to pull the two ends together worked well. One other tip I would mention is I used door shims to prop the pump up above the chain case access door under the bushings. Made it easy to get the access door out and in. Anyways, the machine is back in service after a very lengthy downtime. My last recommendation is to call a hydraulic shop for parts. These guys have communication channels between each other and can find parts fast, much faster then I can on the internet. Big thanks to PSI fluid power in Edmonton. Absolutely awesome service.