b3 vs b6 thermostat-any difference?

[funky technician]

just wondering, where should the needle sit on the gauge at op. temp. ? My B6 always sat at half, this car (b3) never sat at half, (partly why i'm changing the t-stat)

[crazyrog17]

Mine sits at 1/3

[bravekozak]

I just bought a Mazda 323, single stage, 150 degree thermostat from C tire.
I have decided not to drive my car in the winter.
I also bought a waterneck gasket at the Mazda dealership.
Does anyone know if the green sealing ring on the gasket goes towards the cylinder head or towards the water neck? I would think it would go towards the water neck, because it has a greater chance for warpage.