Let me know what your quest yields. I haven't been able to find anything in the old literature that states that these were an option. Nonetheless, they are great looking wheels!
To further muddy the waters ... I have a '97 355 Spider (as of yesterday) and it has the modular Speedlines. Of course, I have no personal knowledge, but the seller stated that the wheels came on the car as an option (did not specify dealer versus factory). If available, I will try to get the original window sticker invoice and let you know what I find.
Congrats on the 'find"........ (and purchase...my gf always laughs at me, as I 'win" something on eBay! LOL!)
Very similar to the TR, and 550/575 Factory modular option wheels. Speedline didn't just dream them up and add them to the line one day....
