Should I rebuild my trans before we take trailer out west ??

Here is my story on a '97 Chevy express 2500 van,gvw of 7800#, with a Vortec 350 engine. I did not own this truck, but was given it by the company I worked for as a service truck. At 49k the trans went out. No towing. They put in a factory reman. and guess what. It went out at 97k, still no towing. They had a local shop rebuild it and I drove it till it had 133k on it in Jan. of '09. I retired and they retired the truck.