the 3500HD GVW is 15000 lbs, more than enough for my purposes, and the axles have the 10 lug rear/5 lug front, with the 19.5 inch wheels (and stainless simulators to boot) with the flared fenders, I'm thinking (hoping) there would be no narrowing of the front axle nessesary. I would like to lower the truck down some (definitely removing some springs, or all and use the 3500HD springs and hangars if possible)....if needed raise up or lose the running boards...I don't want the truck too low, I don't care for the lowrider look, and it's not practical for my use or our roads. I just want it easier to jump in and out of all day.....basically want a Nice Looking Trailer Puller, that is Practical and safe at highway speeds...in the future I may tackle a 4BT conversion, but that's far off. Yes, The truck was a fire truck, then donated to the municipality and was used with a flatbed for a few years, until I acquired it as a Cab & Chassis. Another option, itf the wheels look small in the wheel wells, is to go with 1/2 ton front fenders with smaller wheel wells, if the axle/tire will fit inside...if it looks like it is going to be a difficult swap, I may just look for other options, like a newer 2 ton axle set, with budd wheels...but would rather use what I already have. Will do some measuring in the next day or two I guess and see what things will look like. I was hoping that someone had already done a similar conversion on a truck like mine, and had some input. Also, my truck already has 11R22.5 tires (in front anyways, the rear still has 900/20, but I do have a set of 4- 11R20 like new here on a Bus.