Very interested to see pics - if the bridge (DFV/vibrato?) is stamped with a serial, then it is unlikely that is original to your Legacy. It's certain no Legacies were produced between '80 - '82 ; they were made from ~1992 forward.
It's possible yours had its bridge switched with an earlier model at some point, since serials stamped on the bridge were discontinued pretty early on around the time period you state (it's also a remote possibility your guitar was employee-built, using whatever old parts were available around the factory.) Do you also have a serial number on the neck plate/headstock? There are people here who could date your guitar with any combination of whatever serials appear, but pics are most helpful