Will this be set on a foundation i.e. basement / crawl space, or blocks ?
Most of the ones designed to be on a foundation will have J boxes underneath those for parks that will be on blocks will have connectors like Merlin described that are behind the siding.
One note, make sure the set up crew has it solidly supported and level. Also there is a bond wire that bonds the two frames together it is usually at the tail end and the lugs and wire are shipped on the unit but putting the wire in the hole and tightening it seems to be too much work for some crews.
Depending on the manufacturer some of these are better than stick built and appreciate in value. I didn't believe it either but, it is true.
Ask the sales guy if they have sold any lately that are just being set up so you can see how they do it. That is when you can check them out.
Alan--

Alan--
If it was easy, anyone could do it.