I ordered 11-862903 lock nut for swivel shaft u-bolt on a bravo transom. I got 11-859116 instead (same as for the 6 bolts holding the outdrive to the bell housing) and none of the retailers I'm looking at stock the first one. Some redirects to the 11-859116. Is 11862903 obsolete? It's obviously two different part numbers, and the original lock nuts on my transom assembly (manufacturing date oct 2020) has Red nyloc on them, vs the white/grey on the bell housing. I'm thinking the nyloc is different between the two?

Also, according to Hardin Marine, the two nuts are different sizes:
11-862903 is .375-24
11-859116 is .4375-20

I don't get it..

https://www.mercruiserparts.com/862903-nut

3/8 vs 7/16 threads

I'm not seeing 11868903 show up anywhere? You sure of that PN?

That was a typo, corrected it. Going to check my new U-bolt, might be that the changed the threads. Still, do you think there could be a difference in seize power of the two different nylocs?

I found this while searching

REC11-862903. Equal to. Mercruiser OEM: 11-134371, 11-82671013

I doubt the nyloc strength varies enough to matter. The strength of the connection is in the metal of the fastener itself.