Hi everyone...I purchased a '38 flathead to put into my 29 roadster. It's clean, spins free, I took one head off and the valves and pistons looked good. Now, my question is...when did they start putting insert bearings in the mains and rods? I've never had one apart and was just kinda curious in case I have to get into the bottom end. I appreciate any info you can give me here. Thanks in advance.