Rusted cab mount: How to fix?

[1600buggy]

So I bought this truck (2006 Sierra single cab) with the cab sagging and I just ordered the prothane mounts and am putting them in. The drivers side went together easy but the passenger rear is giving me trouble. The nut that is welded into the body itself rotted off and it looks like someone may have "fixed" it. I was able to jack the body and get a wrench onto the nut and separate and remove the old mount but now of course there is nothing to hold the body to the frame in that corner. Is the weight of the body enough to hold this one corner down? I would squish the new mount on the support so it would not fall off, but it would not be connected to the body. I like doing things right so this would bother me. My other idea is to weld it back up as shown in the pictures. My only concern with that is the cab then being to high and not matching the bed. In that case I would probably shave down the mount itself to compensate. Also on the driver side rear mount there was a cup of sorts attached to the body that the mushroom and rubber went into did this price rust out too or did the passenger side not have one. I can post a pic if that didnt make sense Take a look at the pics and tell me what you think! Thanks!

[1600buggy]

[1600buggy]

 

This is what I was thinking. Weld the nut to the top side of this washer. Then weld the washer to the body of the truck. Yay or nay?

[1600buggy]

 

This is the nut I have

[1600buggy]

Anybody see any potential issues with this?

[Silverado4x4]

Anybody see any potential issues with this?

 

As long as you get good weld penetration but its going to be hard to do as the cab metal is thinner and rotted then the thick washer so you might just blow a hole in the thinner cab metal. I would just cut a panel in the floor from the inside to access the mount and fix it that way then tack the panel back in.

[Supreme Pizza]

I'm not 100% sure what i'm looking at here, because I cant see the OEM design. Can you post a pic of what its supposed to look like, and an exploded view parts diagram?

 

I think your trying to attach the cab to that circular mounting post. I would get a very large metal plate and put it inside the cab (under the carpet), and put another one under that mount. Drill holes through both plates. Then I would use a large grade 8 bolt & steel washers to pull the plates together. Plenty of Locktite or ThreadLocker on the threads. If you need rubber in there somewhere, just fab something up. Tennis balls, cut up a tire sidewall, wrap a bungee cord around the bolt, and duct tape it in, etc.