Used Aristocraft 'might' be easy, or might be a nightmare...
You may find it is wired in different colours to any information you may find for the loco.
It may well have already been 'messed' with, so there might be the odd 'gotcha' if you are not careful.
But if you work through methodically, you should be alright.
Being in the States, you may even find a lico/decoder combination that will just plug in. - We don't tend to be that lucky over here.
Get yourself a cheap meter, and you can 'bell' out the wiring. - Test which wire(s) come from pickups.
Connect just these and the wires to the motor(s) to start with.
Run on blocks (if there are two motors) to check both sets of wheels are running in the same direction.
Lights on early models can be a PITA!
A mix of bulbs and LEDs, and often common negative. - DCC uses a common positive for accessories.
Good luck!
PhilP.