Those teens were one tough engine. Have had and sold alot of them in trucks that pulled hellatious loads.. Had local wholesale grocery company here that ran 6 D500 trucks with 14 foot cube vans for grocery delivery in a 200 mile radious of town here and use 318's. When these truck were traded in the local farmers bought hem and put 14-16 foot grain boxes on them and 300-400 bushel loads of 60lb per bushel wheat to market with them. Many local farmers used them to in pickups to pull 16-18 foot stock trailers down the road with loads of cattle to market. There were vertually bullet proof.