GMC Repair: 95 GMC S-1500 jimmy 6cyl 4whl dr transmission, automatic transmission service, torque converter

Question
shifts fine into 1st and 2nd then just revs up and want go into drive or overdrive.

Answer
From this point on, I will recommend doing/having an automatic transmission service once a year. This includes filter, gasket, and flushing the torque converter. Have you had this done recently, or on schedule? I recently had this problem.

Other than a rebuild, try shifting manually. I had to do this. It worked rather well. Just make sure you run the RPMs up a little more than you usually would in second gear. Also try putting in some Lucas brand transmission conditioner.