What is a thermostat adapter ring?

[KWZ]

So, I'm trying to get my '48 Special on the road after many decades in hibernation.  I pulled the water outlet elbow off the engine and some genius removed the thermostat years ago.  When I looked at the exploded view of the engine contained in the parts book, it shows, in addition to the thermostat, a "thermostat adapter ring," part number 200161, which is also not present on the car.  So, what the hell is this ring for, do I really need it, and if so, who has one?

Thanks,

Kent

[kaiserfrazerlibrary]

The ring is used to position the thermostat in the pipe and keep it from going down too far.   As the picture shows, there's not much to it. 

[KWZ]

Got the ring and the thermostat.  It was pretty self explanatory once I had everything in my hands....