I would bet it has something to do with Canada, not that its because of the windsor plant but some sort of highway thing or rule back in 73.
Does not have the arm rest now or never did have an arm rest? Any broadcast sheet?
Windsor plant did have codes that were not common to USA plants However, a code of CGWQ and the incomplete C56 code is probably not a valid code even for them. Probably just a screw up.
I concur with 69Coronetrt. The only things that are supposed to be in that area of the tag are three digit option codes. This is simply a mistype - very rare - but just a simple mistake that did not get caught - or got caught somewhere down the line but was not corrected. The assembly line workers probably just referenced the buildsheet and figured out what was supposed to go on the car.
KiwiGTX - I would double check if possible whether your car really came with the center console - or if it might have come with the buddy seat and was switched to a center console set up (which would involve changing from a column shift setup to the center console slap stick). 69Coronetrt's reference to the WQ being close to 21 makes sense. Your car should have been coded either C21 C56 for buddy seat/buckets, or C16 C56 for center console/buckets.
Scott.