I have all the racing MkIIs and MkIVs and MkI.
The MkIIs for some reason(cost cutting) don't have the front end and spare tire hatch hinged. Front headlights seemed pinched at the front. The MkIVs are the ones with the glaring faults. Both SAI cars have the same engine cover as the H-M cars, meaning stepped rear spoilers and wrong oil reservoir access ports. I corrected these on my models:
The reason for this, I was told by a fellow at GMP, was they were denied access to the #1 MkIV at the Indy Museum while the Shelby Museum in Colorado gave them full access to the #3 H-M car. The yellow #2 also has the wrong outside mirrors, they should be Vitaloni's. I corrected this by making copies of the ones on Tamiya's 1/12 Lola T70 coupe. Also, the Sebring winning #1's engine cover in incorrectly rear hinged, like the LM cars, it should be front hinged.
All in all, I wouldn't sell my models. If you can find any, I'd get them.