Hi All,
I haven't read about anyone installing any of the seat track extenders to get extra leg room. I bought a set to install in my '70 GTO. The short answer: The extra leg room is really nice, but the installation is nowhere near as simple as the vendors make it out to be.
So, I decided to document the experience and make it available for anyone interested. I have it written up in .PDF form and it's too big to post as an attachment. So, here's a link to download it from my family web site.
http://www.ljklusza.net/Seat%20Track...stallation.pdf
I'll keep it up for as long as I can. Enjoy.