-54 was with the wind chill, -38 or -40 was the actual air temp. I've had people say that they have experienced -10 degree wind chills and they think that once its that cold that it all feels the same. Believe me that -54 is a whole different level of cold. Even with the Cummins plugged in, everything else is pretty stiff. Power Steering, Clutch, Brakes, trans... When it is this cold, I start her up and get her idling fast, I put the transfer case in neutral and shift the trans into 4th gear and let the transmission spin for a while. Letting the transmission warm up before driving and shifting it keeps it from grinding when it is that cold. And since my '02 has a live front axle (no disconnect) you can really tell how stiff that front end is (thick fluid). On ice with a stiff front end, I pretty much spin like I'm power braking. I have to put her in 4hi just to get the truck to move without spinning. Fun fun. A heated garage is on my wish list.