"Ray Heindl" wrote in message

As far as I know the grill has always been run on natural gas, so I
presume the regulator and valve were designed for that. Where is the
orifice located -- in the valve/regulator somewhere?

Valves


When I've bought replacement burners and venturis I've always
specified that it was for natural gas, but the sellers have always
assured me it doesn't matter.

True. The burner is the same, the orifice takes care of the mix along with
the venturi adjustment.