Do OEM main bearings have date codes?

[hubleyman]

Just for fun and out of curiosity, is anyone here familiar with date codes on SBC Main Bearings (if there actually are date codes)?

I just pulled apart the 302 block from my (October ‘68) 69 Z/28 and while I think it has never been apart before, I was wondering if the codes on the Main Bearings would help determine if they are factory original parts??? They are all standard dimensions of course….

Here are the codes from the front main cap bearing halves:

Both bearings have these codes on them:
GMM400
Capitol A inside of a circle and 55084

Plus:
One bearing half has 171P8 and the other half has 269L8

Do these codes make sense to anyone???

Thank, Charlie