1967 Dart GTS Whats it worth

'67 Mopars don't bring as much value as '68+ because of the whole lacking serial no. thing, for the same engine/ trim package, but because this is a GTS, I'd say the values are about the same as your '69 car.

We sold a gorgeous '69 Swinger in B3 with a rubber floor, old lady car with 58k on it showing, and it did show. It went for about $24k

If the car really does look all original, there are ways to check for originality on cars that don't have serial stamped castings. You look for the right date casting, look for the correct cylinder head markings, valve covers, intake, trans date, etc.

Chebby guys typically have to go through all sorts of provenance to prove that they've got something, like a Baldwin, Z28, 409, SS or Yenko car that is correct and as original as possible.

I think the '67 Dart is gorgeous. Especially the GTS. If you do your homework, look for repainted stuff, poke around at odd details like throttle return spring brackets, coil brackets, the K frame, mounts and anything else that is difficult to reproduce accurately in the car and it really looks like the GTS is legit, I'd go for it.