I have a 68 GMC with a goodwrench crate motor and a 700R4 trans installed by a previous owner. I've driven this truck for 7 years with no problems. I drove this truck to work one day and when I drove home in the truck it wouldn't shift out of first. I checked the fluid and it had plenty. When I put it in gear it sounds solid and pulls fine. It has reverse and 1st gear. It just will not shift up. I have not seen any electronics on this tranny. It does have a cable. I don't know what year of tranny it is. I've never worked on an automatic trans. before. Any help would be great.