Thermostat to small for airgap intake!!

I was wondering what thermostat I need to go on my airgap intake. The one I got from summit which is a Milidon high flow will almost fall completly into the intake!! I just read on the Summit how to install page on the intake, that I need the early style water neck.It didnt say anything about a different thermostat.What do I do? What did some of yall use?