I thought I read on here that the t-case are the exact same on those two trucks. The f250 is a new arrival at the jy so i can buy whatever i need but i would like to keep as much as I have to keep the cost down...

My axle code is 39, I think thats full float 10.25 with 3.55's

She will go faster than 55, but that seems to be a sweet spot. The engine sounds good and runs about 2250rpm at that speed. Anything faster seem to sound like its racing the engine. Maybe I'm just used to my 5.0 with OD in the f150.