Going to install a Garmin yaw servo. The installation requires an aft mount that attaches to the top plate of the bellcrank/tray assembly as well as the aft end of the two longitudnal floor ribs. The plans require removing four #4 rivets attaching the ribs to the bulkhead and reattaching the bracket again with rivets. That's fine but seems odd that the bellcrank/tray assembly is removable but will no longer be so if I install rivets to the yaw servo bracket. Instead, I'm going to install with #8 screws and nuts. So today, I dove into the tail and removed the four rivets and drilled out the assembly to accept the screws. No doubt, once the assembly is in place, it will never come back out.