Hi there, I'm new here so please be kind.
I have a 78 K10 4X4 with a TH350 with a 305 in front of it. It currently doesn't seem to have 2nd gear. It worked fine till one day, no slipping no noise. It just shifts from 1st to 3rd, also it won't stay in 3rd when you let off the gas. It will shift back into 1st and stay there till you shift into neutral then back into drive, then it'll go back to 3rd. None of the other gears slip (it will power brake fine in 1st and reverse). The fluid isn't burt, I haven't pulled the pan yet (As I don't have anywhere to do it at my apartment). I do have a place to work on it if need be. I've rebuilt severall motors, so I'm mechancally compentant (just not with automatic transmissions

). Any help would be appreciated.