[6600DURAMAX]

Need a little help - have Blueprint Engines LS3 with the CVF front drive kit -

Originally installed a vintage air 186 degree (part number 707171) thermostat with a Summit - SUM-370998B swivel thermostat neck - this setup resulted in a slow drip from the bottom the the thermostat housing.

I talked to CVF as t I thought I might have the wrong setup - they said all their kits run LS1 stuff and gave me part number for Mr Gasket Housing - 2670 and the thermostat 6367 part number ( 160 degree which I actually like better anyhow )

When the Mr Gasket neck and thermostat arrive I did a better job of dry fitting it and it doesnt appear to fit?
You have to push ( or compress) the thermostat spring to get it to seat flush then it appears the gasket doesnt fit into the housing correctly ?

What am i doing wrong ?