If your truck is one of these trucks, then no it is not a K25, it would be a V2500. Heavy meaning it would need to eat fewer carbs I guess. There is no such thing as a heavy. Also, an axel is really an axle, yes spelling counts. I'm having a hard time understanding what you are asking about your springs. What is zero positive and crazy positive? You need to post some pictures of what you are talking about. You can ballpark your gear ratio, however, it is a good idea to pull the cover and inspect as well as change your fluid in there if you are unfamiliar with the truck.