it is a mystery, even the way the 88LJ is formatted doesn't match anything I have been able to find.
I got the same response from Chevellestuff, weird numbers, no idea. He thinks maybe the year is 1988, no idea what the LJ is.
It could be from a truck. I have a 396, I can't access the block numbers so I don't know what it is, although it is unlikely they are from the same vehicle.
Not really important, just curous.