The Stovebolt Site Forums The Shop Area Engine Shop Rod bearings

So far as I know all undersize bearings are marked so. Sometimes in ink and sometimes stamped. From the photo the bearing looks to be in good condition. You could stick it back in and check the clearance with some Plastigauge. That would tell you two things: if the crank is ground under size and if that bearing can be reused. I don't know what the lead time is on rod bearings but Mains are both expensive and some (55 2nd and earlier) are hard to find. Anyway you could have a new set on the way if you choose to replace them. You might find std. bearings harder to find than undersize. I bought 0.010 undersize bearings 2 years ago and they shipped right away.

If the crank is std. but worn 0.002 or so and still round, you might find 0.002 under bearings, saving a regrind. GM used to list these in the parts book. Failing that you could carefully shim the std. bearings with tapered shim stock if you can find that. I used up the last of mine shimming mains on another engine and haven't looked for more lately. It's a reliable method for setting clearances and sometimes necessary to save a crank compensating for sloppy machinists.