My Peavey Studio Pro 112 TransTube (1995 or 1996, I believe) has an 8 digit serial number without a prefix. IIRC, some time in the early 1990s, that serialization system changed. And in the lower right hand corner of the nameplate is the designation 84C, which corresponds to the year indicated in the serial number. So, for example, my Bandit 65's serial # is 4A-01900152, so my Bandit 65 was an amp manufactured in year 4 of the 1980s, i.e., 1984. And in the lower right hand corner there was a number and a letter corresponding to the year the prefix indicated. That was followed by a letter, which IIRC ('If I Recall Correctly,' in case you were wondering) indicated the type of gear in question. (Updates to be made to this list as new data becomes available.The first digit of the prefix was a number, indicating what year in the decade the piece was manufactured. The Chronological History of MESA/Boogie ® Amplifiers

Walkabout rackmount unit with serial number decal on the underside of the amp towards the rear Mark IIB amplifier with tech initials and assembly date on the underside of the amplifier between preamp and power tubes

If looking for a specific date, you may find an inspection date written on your amplifier's chassis by one of our technicians (as in the photos below of both an older and newer chassis). We build in chronological order (smaller numbers first). The following list won't provide an exact date for your amplifier but will indicate when specific amp models were in production. While our focus has been on innovation and building great amplifiers, record-keeping wasn't really high on the list of priorities until more recently. It wasn't until the mid-nineties, when we started putting serial numbers into an electronic database, that we had more than the collective memory of the MESA crew or an amp itself to turn to in determining when an amplifier may have been built.

Peavey amp serial numbers lookup