They probably will not be identified as a 1918/55. Mine was not. Look for serial numbers over 250,000. Standing by themselves, they do not stand out as being different. Keep a copy of the earlier comparison photos I posted here so you're sure. Don't help the seller out, they find out only 13,000 of them were made the price will go up.
I currently am watching another bayonet that actually is listed correctly (not Swiss) that I'm hoping to snag. This is also a bayonet which has proved elusive for me to find and I didn't know this one existed until about a year ago. Not particularly rare but mislabeled constantly and it's another I don't think many know about as they have it confused with another close variation. If I get it, I'll post it.
Lost out on a knife point cut 1903 bayonet today. Sat at $53 for a week. Sold for $129 in the last 5 seconds. $28 over what I really wanted to pay although I did go a bit more. I was still at least the third highest bidder, not the second on this one. Few years ago when I was ignoring these, they were $60.00.