Yes...
If that square ring was inside the case as shown in your top pic, you have found your problem...the ring is supposed to fit into the small lip depression cut into the outside bolt flange....
Your last pic with the ring on the housing is as I install them...a little run of sealant around the ring just before its installed will aid the seal....
Also, it also helps to have sealant under the bolts that secure the casting to the trans output flange....
BTW...I would grab a brand new square ring,,,it may have shrunk sitting around....
