Dometic A/Cs that are bolted down from the top?

My A/C has no provision for mounting with long bolts thru the plenum. The A/C is mounted with four lag bolts thru holes in the A/C and into the roof. I have it off right now. This A/c the residential quiet cool and has NO plates, panels or anything else inside the RV except for ceiling air returns and vents. PS: lag bolts are a courser threaded and have no nuts.

21 year Hook pilot. IP at M. Rucker in the 70's. bqtoot yours is mounted as you say, mine and I guess other DRV's are mounted with the lag bolts. Not as nice as a bolt.

I have my A/C out for roof repairs at the moment. What everyone is saying is correct. Four lag bolts which are secured from the inside of the camper, thru the plenum, but NOT thru the plywood roof. If you can picture this, the A/C unit sits up top over a square hole, from inside the camper there is (in my case) a metal plenum which sits under the same square hole. The four bolts go thru the metal plenum, up thru the square hole (not thru the plywood) and screws into the A/C unit up top. As you tighten the bolts, the plenum and the A/C unit get squeezed together like a sandwhich in a vise thereby squashing the foam seal on the bottom of the A/C unit creating a good seal against the roof.....gotta love those CH-47 guys at Fort Lewis with thier "Gutentight" torque LOL!

the bolts are in the inside of the gasket

How are the lag bolts sealed to prevent leakage into the roof planking?

Not really. Use German torq value, Gutentight. Had mine in for warranty work, not enough airflow through ducts from main a/c. Tech had to remove a/c and seal ducts. Then the rains came and the leak started. There are 4 lag bolts that are screwed in from the top, under the top cover. There is a foam type seal that sits on a plastic plenum that separates the in flow/out flow of a/c. Might want to have one handy before you take the unit out in case it tears. Mine is attached to the bottom tray of the unit and just sits on the plastic plenum. Just tighten it till it feels right, no real torque value.

they bolt from the inside out and are hand tight quarter turn tight do not over compress the gasket