I'll play the dumb one here, and say that I have never heard of this option to send your car to Goodmark for bodywork. I thought Goodmark made body panels, but never heard of anyone shipping the car to them for work.
I'd like to hear more on this, as my two original rear QPs look good but might be cardboard-thin in reality.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?