Looking at the face and the ring, I would say that is a regular hardware store variety pressure gauge. Would a high pressure oil gauge work, or do they need the liquid to operate? Might be worth a look.
Cage Up, Wheels Down
All my Jeeps are in pieces!
[img]/wwwthreads_images/icons/crazy.gif[/img] Every diesel truck with air brakes has a flush mounted air pressure guage.[img]/wwwthreads_images/icons/crazy.gif[/img] The truck wrecking yards are loaded with them.[img]/wwwthreads_images/icons/smile.gif[/img]
Quadra-Tracs modified While-U-Wait by the crack moonguy[img]/wwwthreads_images/icons/wink.gif[/img] Quadra-Trac Team.[img]/wwwthreads_images/icons/tongue.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img]