I have an Atlas O 1374-1 Union Pacific Non powered C-630 I picked up in February. Had the exact same question and found the answer here. As @prrhorseshoecurve points out, they have the pick ups and in mine there’s wire going from each coupler, through the interior, connected via molex connectors/plugs at the end of each wire aka the middle of the train.
I wanted to do some kind of upgrades- at least add lights. However, when trying to remove the frame I think THREE, at least two, of the body screws became stripped/stuck. Considering the sensitivity of the loco’s details I just put the other screws back and left it as is.
best of luck to you with your unit! Hope you enjoy it!