Another Thermostat / Housing question.

Chrysler has used two sizes of stats over the years; a large in most of the LAs and a small one later in life, apparently 1979Up. There are just the two sizes.
Your intake accepts the one you have which appears to be the small one.
The housing you show, appears to want the large one.

The older intakes did not have the receiver groove,which was in the stat-house.
The later intakes had the receiver groove in the intake, and none in the stamped steel stat housing.
You simply have the wrong stat-house.

FWIW
I never use RTV sealer here, it's a royal pain to clean up. If the parts fit right, there is no need for it, Use the proper non-universal gasket without the slotted holes. Better yet make your own gasket out of thick gasket-paper. Something around .030 minimum thickness, thicker is better until you get to .062 maximum . Those slotted gaskets are junk;if they don't leak on day one, a 15psi cap will squeeze coolant into there in a short period of time and then it will come up the bolt threads. That's another reason I run a 7psi cap.
And only a light torquing. Actually all of my aluminum manifolds get studs in this location, and I bet you can figure out why. For starters they have NF threads on top and require less torque to stay tight. But more importantly;with bolts,if they leak, the first go-to is to make it tighter, and eventually the threads will give up and pull out of the soft aluminum, and then you are walking. I hate tow-truck rates.
And I use those exhaust manifold end-stud washers, that Chrysler put on there. They distribute and retain the clampload.I use no lockwashers and no flatwashers, only these special washers.
Using these tricks,I almost never have a leak at this location, sometimes going for ten years or more.
Good luck to you.