Re: Cat No. 9 Auto patrol
If it is indeed a No.9 it should have a serial number tag on the frame rail (left side toward the front where it makes the downward bend) that should bear the "8A" prefix. The No.9's used the Cat 4200G gas engine that was also used in the L and PL series Twenty tractors. The main and rod bearings are all poured Babbitt with removable shims for setting clearances, and the crankshaft drillings that distribute oil from the mains to the rods are supplied by oil tubes that have soldered fittings on the ends that banjo bolts go through. Each main bearing has an oil line feeding it where the oil then finds its way into the drillings and flow out to the rods. A common problem on these oil supply tubes is to have the banjo fitting come off from stressed and cracked solder, and in the worst cases the line comes out of the fitting completely and starves that main and rod journal of lubrication.
Parts aren't extremely hard to come by since a fair number of Twenty tractors were built and they use the same engine. One nice thing about babbitted bearings is that if you can manage to get the affected crank journal rounded back out and smooth you can always have the bearings poured and line bored to fit it. Usually good used parts can be found with the exception of manifolds - the exhaust, intake, heat box, and drop tube are all usually deteriorated and in poor shape.