I recently purchased a Troy Built Horse for real cheap, because the egine had no compression. Few days later when I got time to tear into it found the connecting rod busted. Like others, I am committed to leaving the original engine on the tiller, so that leaves no option but the repair. Plus, I might get my wife to use this since it's got electric start.
So.....I ordered a rebuild kit from a guy selling them on ebay for 69.99 plus S&H. I'll be getting a new piston, rod, rings, and gasket set. I think the connecting rod it comes with is the 3180C. I'm guessing the 37450 is the original part and the C is an aftermarket. Plus, from the photo's it looks as if the oil dipper config is slightly different. If it interferes it's nothing a file or grinder won't take care of. I can always fashion my own dipper out of some sheet metal.
I'll post a reply to update you all (if anyone is still reading this thread) to see if the C version of the rod works. Actually the rings and the piston are in great shape but since I've got it out I'm going to hone for about 30 secenods, re ring it. Since it's cast iron the walls are not scarred or ridged at all. Also planning on pulling the valves and maybe clean them up with some lapping compound.