I was pulling a Jet boat (with a 455 Olds in it) the other day up a long grade and I noticed smoke pouring out from under my Blazer. I let off the gas and took it easy for a bit and it quit. Was kind of hoping it was a one time deal (very wishful thinking) but no go. It did it again today while pulling a trailer with a John Deere garden tractor on it. It's the transmission. Fluid was all over the back window and sprayed everywhere underneath and the fluid is very dark and smells burnt now. What in the world is going on? The truck has 122k on it. I just changed the fluid (Shell Dexron III) and filter this spring. Do I need a tranny cooler? How much are these? How much trouble are they to install? Any thoughts, ideas, experiences or words of wisdom will be greatly appreciated! Thanks, Pat.