You can't track down an electrical drain by testing voltage. You need to test the amp draw on each circuit.
I have posted it before in threads very much like this. The steady state amperage draw should not exceed 35mA. I say steady state because there will be a period of 2-5 minutes where some of the modules in the truck will still be fully or partially awake. The amp draw may be over 2A to start off. After 30 seconds or so it should drop to around 1A. From there, it should drop down to below 35mA.
Start at the battery and see what your current draw is. Then move to the individual circuits.
Have your battery load tested as well.
You don't need wiring diagrams until you have identified the circuit(s) that is(are) at fault for the drain (if you find one).
Isn't "exactly similar" a contradiction of terms? LOL