I was able to install 7x7 seat bases right over the dreaded r&r design bases. Installed a drain hose for the front deck seat base, the rear didn't need one as it drains into the livewell. I drilled holes into original base, threaded them, and installed ss heli coils. Secured with 5/16-18 machine screws stainless. Blue loctite. The 2 middle holes I used the original bolts to hold the new base to the r&r, and all that is secured onto the deck via r&r original rectangular brace