Buying or Trading maybe

My Friend Todd Offered to sell or trade me his 2000 Peterbilt 379 With a Cummins N14 in it for 40k and he just had turbos and batteries and wheels replaced. The Truck is well taken care of it has 850k on it but its small and he also offered for me to trade him my freightliner classic xl 14.0l. He says that he is tired of the his pete because it so small in the inside so i told him i would buy it or trade him my freightliner classic xl. What should i do because if i buy it i wont drive it and my main truck im driving is a coronado but I do want to get rid of my classic xl