This is a complete replacement for old Thetford waste dump valves. It has a flat-top for direct mount to a Thetford tank flange. On the bottom outlet side, it has a 1-3/8" long 3" spigot (3-1/2" OD). Made of ABS, the spigot is designed to be solvent welded into an ABS hub with a 3-1/2" ID. Top seal and four mounting screws are included.
This valve is just like the 08708 except requires a Thtetford extension handle (sold separately).
This is version 08709 of Thetford valve 01447. Every Thetford valve ever made says 01447 on it, so you can't rely on the number molded into the plastic to guide you in selecting the correct version.