I do not claim to be a mechanic by any stretch of the imagination, but I do love old trucks. I own a '51 Chevy 3/4 ton pickup and am learning restoration as I go along. My '51 is geared very low and has trouble getting up any speed on the highway. What can I do to improve this? One person suggested changing rear ends. He said change the pumpkin. To me a pumpkin is something to make pies out of. Can someone set me staight? Thanks.