The guy who said that truck is worth $450 used was on crack. I bought my Revo for $400 new from the local hobby store, and its Traxxas newer truck than the t-maxx. And Savages are closer to 375 than 400.
That trucks clearly been run, and not a little, or not lightly. Likely neither. Those body scratches come from more than the break-in period. Its been jumped, rolled, etc. Hell it looks like its missing a piece off the cooling head, the plastic ring that snaps in.
Also, that nitro fuel attracts water notoriously. The fact that this moron sent it to you with fuel still in it is not only dangerous and illegal, it may have ruined the truck. I wont leave fuel in my truck overnight, hell not more than a couple hours (although Im anal about it). It will collect water, and that will corrode your carb, valves, cylinder, etc. There's a good reason you drain them of fuel and purge the motor using oil -after each and every use-, because they need it. Those nitro trucks are touchy, and take strict maintenance, something the previous owner -blatantly- ignored. The minute I saw fuel in it, I would have demanded my money back. The kid who owned it before you was a lazy moron who treated the truck like garbage, then handed off what's left of it to you, as 'BNIB'. You got shafted, sorry. IMO if you're smart you'll demand your amp back, unless he's already trashed it too.