I'm pretty sure it is an 1/8" NPT port in the trans case, Not sure what psi range gauge you need, John will chime it. EDIT I Googled it & they said it starts at zero & goes up about 1 psi for every 1 MPH. I'd get it up on stands, plumb the gauge in with some cheap plumbing pipe fittings & run it up & see what you get. Those gauges are reasonable.