The antenna does not work with v8, but supposedly all prior versions. Nowhere is this documented, but if you're looking at your router make sure the serial number doesn't start with CDFF or CDFG.
I had a thread posted about it, but apparantly questioning it was too risque and it was deleted. Didn't know it was wrong it ask why this isn't documented and why they changed the router on the v8 to not have removable antennas.
I just bought one of these today at Best Buy to replace my V2 WRT54G which mysteriously died. I was highly annoyed to say the least. My high gain kit which is MADE FOR THE WRT54G cant be used, which makes this router useless to me because I need the range extension. I called customer support and got the worst runaround I have ever had. All I wanted was for them to explain why they changed it, and get me one with the TNC connectors so I could use THEIR product designed for this model router. 45 mins later I am disconnected mid-sentence from their customer support and typing this message so please understand me here:
1. The back of the box shows the old TNC style antennas
2. There is no notification of a change in antenna design on the outside of the box
3. Customer support utterly failed in getting me a remedy to the situation
I used to install these routers for customers and recommend them all the time... I think I am going to change my mind about that as of tonight.
I don't know why they changed the router to use non-removable antennas, but if you look in the Product Specs for the HGA7T (Hi-Gain Antenna replacements), it says on the second page for the products supported, that only up to version 6 of the WRT54G is supported by the HGA7Ts. So, my guess is they want you to by a Range Expander, like the WRE54G, to get greater coverage. I noticed from reading this board that many people were purchasing the antenna kits and complaining they weren't working as advertised. Maybe they had many problems with people trying to manhandle the antennas off and on to the unit and had many breakages - so they stopped that problem by making them non-replaceable.
FWIW, I am in the same boat as lots of OPs here, since I have a WRT54G v8, and really was wanting to just add the hi-gain antennas as a fix for poor coverage in one room at the opposite end of the house. However, it looks as though that's not an option any longer.
The only place I could find where it talks about the antennas on the WRT54G v8 is in the HGA7T Product Spec blurb, on page two, which says it only works with v6 or earlier units.
I wanted the HGA7Ts to solve a small problem without going into getting range expanders, etc. - too involved. Alas, that isn't going to happen!
As for Linksys Tech Support, I have used the Live Chat consistently and those folks have been most helpful. Anymore, if I can do a chat, I prefer that over rude humans any day. Over the years, I have heard not-so-nice things about Linksys support, but recently heard it had improved when Cisco took over them. Guess that was a little premature!
The one nice thing now is that this gear has come down so much in price that you can almost afford to just toss a unit and buy another one (brand, model, etc.) to use. It kind of stinks that backward compatibility is not possible for you, but I guess they're in business to make money, and you can't do that by supporting a bazillion "old" versions of something, even if customers need it... best of luck!