Richard what makes you think that is a early late thing? My son-in-law's SJ coupe built Sept. 1966 had the stainless steel ones. I always thought it might be a plant or supplier thing. This parts car is a early 67 Dearborn car.
I believe it is early/late based on personal observations and researching for my Nov. 66 San Jose build. I am open to discussing details found on other example that include a Marti Report confirmation, which might help wash out certain non-factory examples (not saying your son-in-laws example it isn't original but also, keeping in mind that replacement tops along the way are very common too).
It doesn't hurt to take a look at drip rails for any holes on cars with a Marti-confirmed example. I rather doubt any dealer or other installer would drill holes for the strips that I consider EARLY (the aluminum ones).
The aluminum strips carry a C5ZB-6553728-A engineering number (as seen in the 67 Osborn Mustang Interior Assembly Manual, page 55, dated 12-16-66). No mention of the stainless version in that citation of reference. A C5ZB engineering number suggests to me that the same strip was designed for the 65 model year and carries into at least the beginning half of production of the 67 year model. I look at this detail on vinyl top examples at shows, and though I haven't complied any list, my research lends to this as another 67 running change of sorts.
