I have a 95 GMC 1/2 ton 2WD w/ a 5.7 liter 350. My auto/trans won't shift on its own and won't even go into 1st or OD,nor will the speedo,tach,mileage gauge,tripometer,or the A/T shift indicator light work BUT WHEN ONE WORKS THEY ALL WORK, even the transmission. I thinks its an electrical short but dont know how to check.

Sounds like you do have electrical troubles. If no electrical power is supplied to your 4L60E transmission you will have 3rd gear starts. Manual 2nd is allowed due to the hydraulics. 1st gear is not allowed. Check the ignition switch, this could be your transmission and gauge troubles.