Just catching up with the past week of posts -- about 2.4s. Surprised to learn this was Thiel's lowest-volume speaker, building on the successful 2.3, with a good economy for the first 5 years of production when most would have sold, and a still-committed dealer network.
As a point of reference, mine are SN 611 & 612 and almost definitely have the original XO: wooden LF & HF boards (literally) hand-wired with Acousti-Coils, AEON electrolytics, bright yellow Elpac 100V 1uF 5% polystyrenes (?), Erse 100uF 100V electrolytics, Xicon resistors, and a Solen PA-MKP-FC in the LF XO. I believe they were AEONs that I replaced with Clarity Cap ESAs some years ago in the coax feed. Rob Gillum built me a new pair of coaxes a couple years ago, so I'm sure I'd be most of the way to these speakers' potential once I replace the resistors. *Most* of the way: I know how far some of you have gone with all the ancillary parts!
When I bought these used from agon in mid-2006, I had checked with Thiel who told me these SNs were early production units with the previous woofer that was later updated, though sonically identical. Never followed up about that, but I'm sure buried in my paperwork or emails is the date of manufacture of these speakers.