Two entirely different factors may control matters in replacing the existing home. One is technical, the other is regulatory. In my area, units made before July 1, 1976 may not be relocated. In other words, it must be left where it is or destroyed. Renovation is permitted. Technical problems are easily solved. Better educate yourself about the local regulations first. Local mobile home dealers probably can answer most of your initial questions.

We did exactly what you are pondering. I agree w/bus driver that the first things to check are the regs for your state and area. There could be set-back restrictions etc. The dealer from whom we purchased took away the older D/W we had, in fact it was one of the reasons we purchased from that dealer. They stuck it on their lot and sold it to someone else. In our case we did not have our old home on a foundation, so we had one built to match the new Home. In general whoever does the site work/foundation can deal with moving the plumbing as well. Just be VERY specific about what you want done, and make them stick to the contract. Shop around and get estimates.