Yes, on the 400 I rebuilt a few years ago I used that kit. It seemed really odd to me too, but I followed the instructions and it doesn't leak.

It does looks pretty crappy though and the RTV really gobs outward toward the main cap. Make sure you push the pipe cleaners all the way down too. When I squeezed in all the RTV I could down the side channels, I could still see light coming though near the bottom when I checked with a flashlight. After pushing the pipe cleaners down it seemed to seal. I also RTV'd the retainer to the block from the back as well.

Like I said it works, but is pretty messy.