That's a Vintage Rat Reissue (not an original). They were made from 1991 until about 2004. Rat serial numbers aren't coded in any way, but I've seen much lower serial numbers on the Vintage Rat Reissues that were made at the end of their production run.
Could Not Open New File Isis Proteus. If you post a pic of the guts, I can pin it down for you. In particular, the op-amp and the codes on the pots (if there are any) are useful. Meh, thanks but I aint that concerned about it.
It's been sitting on a shelf for a decade doing nothing. Another decade won't hurt. We will still mod Rats with serial numbers under 300,000 (pre-early 2008) for $65. If your Rat's serial is over 300,000, we'll mod it, but we have to charge $99 because of the extra work these units require. He's referring specifically to Chinese made RAT-2s since production moved from USA to China well before 2008. Rat serial numbers are not recorded and are only vaguely sequential.