What causes "dieseling"

It started life as a step side but either the factory or someone put the tool boxes on, which is the main reason I bought it because I wanted a tool truck because I am too lazy to lug heavy tools everywhere I go.

I'm not sure what a fleet side is but it is a shorty.

At this time I am not selling, because I want to play with it.

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That thing is cool ! You should rig up a swivel crane with a boat trailer winch in one corner of the bed. If for nothing else, it would make it easy to get the floor jack that weighs more than you do in and out of the bed. :)