I've fixed 3 of these. They were all leaking on the right front corner of the intake gasket. (Passenger side). Fluids seek their own level. So the coolant level inside the radiator should be at the same level as the leaking area. They tend to leak when cooling down. I guess the heat expands and tightens everything up.
A upper gasket kit used to be in the $100 range. The hard part of the job is pulling and getting the distributor back in the right spot. I could probably do one on a pickup in days time. A MH, I have no idea. I would think a shop could do it in a day but they always have scheduling problems and other things to work on. So I'd figure on at least 3 days in the shop.