Chevrolet Repair: 1989 Suburban transmission, suburban 4wd, streaches

Question
My 1989 suburban 4WD, 350, Turbohydro 400? has started shifting into high gear very early. This only happens when the transmission is cold. Fluid level is good. Do these things shift by vacuum? It seems I replace a modulator on this transmission before. Could a bad modular be the problem. Any other suggestions eagerly sought.

Answer
Hi Tom....try setting the TV cable...if you look at the cable where it comes up from trans to throttle there will be a button on the cable... push that button in and open throttle all the way. then release button...you might need to do it a couple times...that will adjust the cable for you early shift...cable streaches over time ...hope this helps