it was in the mad scientist tool box. we were looking for a fuel pressure gage but t
is doesnt seem to fit the bill

 

ya know, im a professional photog, so i have to apologize for the crappy photo, but my camera gear is at work and i dont want to get it to the garage....

8)

this thing was in the same drawer as the fluke meter, the pyrometer, the stethescope thing, and other assorted mad scientist tools....

 

It sort of resembles a fuel pressure gauge used on older GM products.... On throttle body injected vehicles and some port injected GM opted not to put a handy fitting for checking fuel pressure... Instead you had to attach the gauge inline with the fuel line..