Auto trans won't shift past 2nd gear. Local transmission shop diagnosed problem as bad 3rd and 4th gear clutch packs. They want $3,200 to rebuild. The truck has 193,000 miles but body and frame are cherry and engine runs great. Should I pay to have it done or junk the truck? The truck is like an old friend but I don't want my attachment to it to get in the way of common sense. What would you guys do?