you have to buy the set but its easy to take the clock off and just install the tach. done it before for customers
http://scp-parts.com/index.php/smartoem
i have the tach and clock and the trim rings. you can use scoa5 in the discount code bar and get 5% off.
clock rings and shipping after teh discount ends up being just under 267.
and yes the are entirely plug and play. how ever you do hve to notch the center trim panel.