I think the finish used on the shrouds was perhaps changed at some point ?? during production. Mine, from June '82 has a matte finish such as may have been produced by blasting with a very fine media. I'm fairly certain I've seen some other examples of the matte finish on the older 7549s.
Thanks, guys. It's not NOS, but is a very lightly used example. I bought it from the original owner a few years back after he had it completely serviced. It generally makes it into the rotation a couple of times a month, but I make sure not to wear it while working on the car or doing yard work. ;-)