My 70 longhorn has an auto t400 trans. It is the first truck (out of about 20) that has an auto trans and I know nothing about them. I have put about 5k miles on it recently with no problem. Yesterday after about 30 miles and a stop at the gas pump it had trouble shifting. Fluid level is fine. It revs way up in first and then jumps into second. It does the same between 2-3 but not as hard. Where do I begin?
