I used a DIY quartz clock kit for my Challenger rallye clock from Real Time Engineering that I bought at Carlisle about maybe 15 years ago. I just looked at their website http://rt-eng.com/rte/index.php/Main_Page
however and it appears they sell tach kits but no longer sell clock kits. Too bad because it worked well for me as the clock still keeps good time. I read something on their website that sounded like they may have sold off that portion of the business.