My "other" hobby is gunsmithing, and collecting antique firearms. A "numbers matching" 98 Mauser rifle with all original parts, including the correct proofmarks and inspector's stamps, in excellent condition, would sell for several thousand dollars. The same rifle, with a "period-correct" stock, bolt, or magazine box from another rifle might be worth less than half. A cobbled-up rifle assembled from original, but mismatched parts might go for a couple of hundred dollars. Same parts, same ability to drop a deer in its tracks, but extremely different dollar value! The average military surplus rifle has about 30 parts, not the thousand or more a vintage vehicle has! It's a lot easier to collect "numbers-matching" guns than trucks.
Jerry