evilunclegrimace
Does not always play well with others
I tried looking up this truck on NADA but couldn't find anything for a RCLB K3500 in 88; assuming it's a fire-department truck (blue light on top?) or some sort of municipality truck, base model with crank windows, vinyl flooring and such...
With 10K miles, and if it's spotless; with a 454/TH400, Justin seems about right, 10 or 11K sounds like it'd be the higher end of the spectrum.
I would just drive the truck as is, I wouldn't tear it apart if it looks that clean in person.
If it was optioned like you described the sticker on a truck like that was under $17,000 brand new.