A-D frames can be FR threading...But they were notorious for offering all the popular flavors, I have seen A-D products with FR, Swiss, BSC and (if you include the Puchs that were contract built in Italy, maybe by Bianchi) even with Ital! You can never assume with that brand, but after awhile you can make an educated guess based on the year (if you know it) and the component group (assuming it's original)...or at least narrow down the options. The models that come with mostly FR parts usually have FR or Swiss BB threads...usually.