100% "home job". There is no practical way to put a lamp into a properly assembled 1682 since the body is held on with tabs and made from a single piece of carefully folded metal. As such, there is no easy way to access any interior bulb without taking the entire thing apart semi-destructively. Lionel certainly would have designed a holder/door (2757 caboose) to solve this if they offered a lit version. Along the same lines, Lionel would have used their regular roller truck and screw base bulbs in the prewar era (plus they would only have used one bulb). Moreover, if Lionel had made it, the marker lights would likely have been celluloid discs like on the 817 or plastic inserts like those used on the 1668 Locomotive. The cupola is also on the wrong end for Lionel production, although this is simply a matter of someone turning the body around when re-assembling it. Also, the coupler also does not look like it is assembled to the frame correctly, but I can not say for sure.
I don't see any signs of forcing it open, it's obvious they took their time.
The tabs which hold the body to the frame are all straightened. While it was done carefully, many individuals will not even consider purchasing prewar/tinplate that has been tampered with in this manner. It indicates (or hints at) restoration/modification/parts assemblage/fakery of the piece. Since the caboose has obviously been altered, it is not that much of an issue here.