I have only owned western plows. The one poster is right that they have made the whole unit to come off for quite a few years. I think western does offer some adapters, that you can mix and match to make older style plows work on newer mounts.
I would guess that the vehicle lighting system is way different. For one you have daytime running lights, among other things.
At least when it comes to western, many of the newer control modules have just leads that actually hook up. There is very little splicing done, it is mostly plug and play. I do not know if all manufaturers are like that, but I would guess they are.