Right, it should have a GI serial number. The special edition was the wood furniture which is a different model number.I got it used, but have the original case, with serial number on it, and it said GI special edition with green stock and hand guard. I don’t reload 308 yet, but probably will at some point.
To mount a bayonet, you need the adapter, which is a spring-loaded plug that replaces the plug at the front of the charging handle tube (yours may already have one installed). The stud on the pommel of the bayonet fits into this adapter and latches into it.You need a bayonet to go with that.