that's a very customized truck. "new custom made harness" would be enough to scare me away
I've found I never really like unscrewing what some previous owner has done (and I'm sure anyone who has bought something I've worked on says the same thing). But it all depends what you want. To your original question - if this is what you're looking for, then just make sure you go in with eyes wide open. I'd ask for a picture of the SPID and compare to the cab VIN plate as well as the frame partial VIN to see if it matches anything - in order to figure out how this thing evolved - and to make sure you know what you'd be registering (and how it is titled). If titled as a K20, you might run into problems with that 1/2 ton VIN - the metal tag VIN is the primary VIN for the vehicle - the frame and SPID aren't as definitive, especially the SPID (because they can be duplicated). The ad does say it has 3/4 ton axles, so who knows what the original frame is from. Double C frame means additional C channel has been added to the inside of the existing C channel shape of the stock frame. Usually associated with heavier duty trucks than these light duty trucks. Personally, I think it would be a nightmare just to buy parts for... BUT, if this is how you'd build your own custom truck if you were going to, then maybe you'd save $ buying this one - it really comes down to what you want and it's a different answer for every individual. I would take the time to ask the question about the frame VIN and SPID. Odds are the SPID is long gone - but the fact that he's claiming it's a K20 and the VIN is for a K10 - I'd want to fully understand the scenario before taking the plunge to make sure you won't have any problems with your local DMV.