Dennis - I understand what your saying about the semi-spherical shape of the outer race of the bearing for the snow thrower, and I understand the 2 flanges hold it true and in place (I've replaced several of them). I also understand the outer race of the PTO bearing is flat and how it sits inside the PTO cast assembly. I was only passing on that I had been told one would work (could be used) in the other. I don't recall which way (whether the PTO bearing could be used in the thrower, or the thrower bearing in the PTO). I suspect it's the thrower bearing in the PTO - because you push the bearing up against that big snap ring, and when you install the PTO assembly onto the crankshaft those 3 little really pointy set screws get screwed down against the outer race of the bearing. As long as you hold the clutch assembly true vertical when tightening the sets screws I'll bet it would work. It ain't something I ever did that I recall, and I don't know if there is anyone on here that wants to try it just for discussion purposes, and I can't foresee a dire situation where in a pinch you would want to do this, I'm just saying someone at a CC dealership had told me it would work.
Hey Earl - have you got a PTO bearing you can slip between the 2 bearing flanges to see if they hold the bearing securely in place - and the flat surfaces on the flanges contact each other???
Jerry H - on your issue with head bolts coming loose. Are you torquing them to Kohler spec and in the correct sequence shown in the service manual? Also, after you torque them to spec, you need to run the engine for about 20 minutes, let it cool down 30 minutes, then re-torque them in the proper sequence again. If you're doing this and they are still coming loose after 3-5 hours of use then you may have a warped head. Before machining or replacing the head you could try new grade 8 head bolts as Jeff noted but I'll bet the same thing happens. The head needs to be true.