TTT............It seems no one makes the replacement thermostat housing, but I took a chance on the GLM 13230 Thermostat Housing. its all the same except you need to mill about 7/8 of an inch off the lower part of the housing and fits perfect. GLM 135 bucks........Mercury about 500....and I wouldn't be surprised if GLM makes the ones for Mercury.

yes they are

Wondering if you actually bolted this up. I tried a glm and found the following.

1. I removed the 7/8" with a cutoff wheel and then finished with a bench top belt sander.
2. When i tried to fit it up the boss on the back side that holds the pipe plug contacted the intake. I had to run a tap deeper in the hole to counter sink the plug and then ground down the raised boss flush. It then went back far enough.
3. Then when I tried to bolt it on the bolts were indexed wrong and it kicked the nipple that the big hose goes on out far enough that there was no way to avoid contact with the belt.
4. My friend suggested that I press steel dowels into the existing bolt holes and re drill the holes to the proper indexing. I went with my idea. I threw that f...ing POS in the trash and coughed up the 5 large for the Merc housing. Didn't want to do it but it was kind of liberating hearing it hit the bottom off the trash can after screwing around with it for the better part of the day.

I truly hope that you have a good p/n there and it works for you. I would like to eventually replace my other 2 but the 500 is a bit salty LOL and I would love a less expensive alternative.

The boss on the rear does need to be ground down also, if you look at the stock one it is welded closed, I'm posting what I'm using, people need to do their home work and figure out what works for them, I don't want someone *****ing at me because this part didn't work for them.....

I am glad it worked for you. I don't remember what p/n I ordered. I was so disgusted when I was done with mine. Will be ordering your p/n next time. Thank for the tip.

I'll be damned. The small block one looks right. The bolts are straight across instead of canted like the big block one. This is good news. The moral of the story on my post above is do not order the big block one LOL.