I have a 58 235 and getting a lot of exhaust smell in the cab which i suspect is coming from the pan breather.
maybe you have holes in your cab and floor and also leaks in your exhaust system starting at the exhaust mainfold. i know on my 51 splasher that used to be in the truck, it leaked big time around the flapper shaft to the point the bushings were gone plus that annoying pft. pft. pft.
