Level kit or not

[Runaround]

I bought an '07 Quad cab 2x4 a little over a year ago. I sits level. Is there a way to tell if a leveling kit was installed before I got it? It has the 20" wheels. I don't think the rear has been lowered.
This truck sits higher than my '14 Tradesman with the 17" wheels.

 

[Sandevino]

Look for coil spacers and shock extenders up front.