Mike,
Here is a link that includes a diagram & parts breakdown of the Suburban 10 gallon gas/electric water heater. The electric thermostat is seperate from the gas thermostat.
http://www.marksrv.com/swwaterheater.htm
Suburban information is difficult to find.
The electric switch/thermostat unit, 140 degrees does not appear to be adjustable. It is available from the above website as part #0520788 for $24.75 It
appears to fairly easy to change out.
The screw in heater element, part #02143 is reletively inexpensive at $12.50. It requires an 1? inch socket wrench though.