I am re-reading this entire thread this morning and again, John's comment stands out to me as basically unanswered...He is saying that his "C-Code" San Jose built GT had dated correct, "fine thread" shocks on the rear. Is this an anomaly? Is it something else?
For normal, typical San Jose built Mustangs (without the export/competition suspension) I would say yes. From what we've seen each plant had certain plants and providers that supplied that particular plant. May have been to cut down on shipping cost, make the resupply quicker or other unknown reasons. From time to time it appears one of the other suppliers products got into that specific plants supply system and things like this turn up. We take notice since it is out of the usual.
Unfortunately most owners do not have the luxury of having original parts so they rely on what has been typically found for a "safe" logical possibility
Is it possible the assembly line shock absorbers (possibly front AND rear) COULD have differed depending on engine application? (are the C-code and A-codes different than the S-code cars?)
Believe that if the buildsheet showed "BROWN" (for example) the worker simply grabbed a shock out of the bin and put it on the car without looking at other boxes slowing up the process. A brown mark shock (and what ever associated engineering/part number was associated with that color mark) would be the same for both applications. If there had been a reason for a difference or was a difference that was important to production I would think there would have been a different identifier assigned to that second shock
I think what we have in John's case is the possibility that a pallet of the shocks marked differently got routed/delivered to Milpitas/San Jose