I have a 1990 gmc 3/4 ton. pickup the transmission wont go into drive. It is as if it goes into nutural. I dont know if tranny is shot or if this is something worth repairing tranny or replace it.
Check the fluid level, if low fill to specs and recheck. If the fluid is dark or black then it is shot, so stop there, if not then continue. The filter could also be plugged, but to get to that you will have to drop the tranny oil pan, and if you do that look for metal particulates in the bottom of the pan especially those with a gold color, that is bearing material and that means trouble. If none then put in the new filter and pan gasket, add 1 quart of TransX and fill to specs, start it up and recheck fluid level, top off if low and see if it starts to work.
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