Autometer mech water gauge install-help!

[87TTopGT]

I just removed the factory sensor from the intake to install my Autometer mechanical gauge, and the fitting is a different size! Anyone know what exact size adapter I need to install it?

P.S.- Is the factory gauge electrical? Had a wire going to it instead of a capillary tube...


P.P.S.- Oops, popular subject, before the flames start I searched yesterday and didn't see anything about adapters. Anybody help out TWO Stangers with this info?

 

[BLOWN 5.0 FOX]

3/8 to 3/8 autometer specialty fitting- dont bother looking at the hardware store they need to be special style compression fittings and autometer sells them for $6 or so. Good Luck