90 degree thermostat housing question- O ring?

[PDQ]

I picked up a 90 degree housing and it's the later model Mustang "O ring" style. Will this still work on the early version manifolds? It will be going on a 5.0/ Pro Flo, so I just want to check if I can/should run the O-ring that comes with the housing as the gasket, or, ditch the O ring and run a factory flat gasket, or, if I need to get a different housing.

Thanks as always

 

[SteveL]

If it's one of those chrome ones ditch the whole thing ago with the standard cast one. I've found most of the pretty chrome ones to not be flat and rarely seal correctly.

 

[PDQ]

Black Trans-Dapt. And standard or not, will the later model o ring styles work fine on the early manifolds? Or are they matched by generation?
Thanks

 

[cldonley]

Pretty sure the manifold surface is the same, the change was the grove for the o-ring in the housing, so it should work for you.