LT1s only use one gasket, and that's the o-ring on the t-stat itself. None for the housing.

 

Yes but all it takes is a little corrosion to form a pit where the ring fits in the channel of the neck, or on the intake, and you have a leak.
I prefer a little extra safeguard, and would have used a thin coating of RTV on the neck and intake.

 

I"ll try the RTV around it.