Transmission for 88 Chevy K2500 4x4
 

I have a 1988 Chevy Cheyenne k2500 4x4. The truck has a 5.7 350 with a 5 speed manual shift. It is my understanding that the first half of the year they made 4 speeds and the other half they made 5 speeds. I am having problems with it jumping out of first gear. I have had the transmission rebuilt less than a year ago and it has been in and out of the shop ever since with the same problem. Obviously the mechanic cant fix the problems. My question is that is there another transmission that will work with my truck. Preferably an automatic.