Looks like a nice little 'cocker. Probably about '96 or '97 vintage. That grip frame looks to be billet machined rather than the more common "pot metal" type. You might be able to get it anodized black to match the rest of the gun. If you want to "restore" it to factory specs, PM me. I have a few of those old stock bolts lying around. The set screws for the timing rod coupler should be available at your local hardware store...I think they're either 4-40 or 6-32 cup head set screws. If you can't find 'em locally, PM me...I think I've got a few extras I can send your way. Also, the LPR is the black thing sticking off the front block. Leaking could be due to a worn or damaged seal or the pressure being set too high (they're internally adjustable through the 1/8" NPT nipple on the end that screws into the block). I've got a couple of them in non-leaky condition over in my FS thread
Since they were set up for high pressure back when this one was made, you don't technically *need* a regulator, but if you're going to run it on CO2, one would come in handy. I'd suggest a PPS Stabilizer. They pop up now & then used, but usually sell quick. Every now & then, PPS puts some on eBay with a Buy It Now price about $5 or $10 below their regular price. Again, they usually go pretty quick. Still, if you can get one, it'll help tremendously with velocity consistency.