I have a 1985 K10 with a 700R4 tranny. Just this last week, I noticed it not going into OD, about the same time, when going down my street at home, it wants to shift in and out of second at slow speeds. The truck has about 110,000 miles and the original owner had tranny work done at about 50,000 miles back in the early to mid 1990s. I understand that third and OD share the same clutch, I dont have any problems with third, so clutch is ruled out. Any ideas?