I have a 97 dually with over 300k miles on it. Has a cracked head and uses about 2 gallons a week of coolant. I average 1 thousand miles a week in this rig and rarely shut it off during the day. I'm pulling a super duty trailer behind it hauling junk cars out of a field all day to the scrap yard. This truck just runs amazingly well and is quite impressive. I change my own oil 2 times a month in this thing and its never more than 1/4th if a quart low.

I been running it with the cracked head for about 6 months now, I have a replacement motor(87K out of a RV), so for now I'm just gonna run it hard till it blows.

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A bit of a funny story: one day the dually was in the shop, and all I had was my brothers fords, and an old ford farm truck down in the field. We was trying to pull an old Chevy van with no wheels out of the bottom. Had a ford expedition 4x4, a Ford f250 v10 4x4, daisy chained to the Chevy, and an old ford f350 farm truck(mid80's) , and with the 3 fords couldn't move one Chevy.