Now normally I'd bang off a patch paint out of some sheet metal, weld it in place and seal it up with some seam sealer. However the body mount part has me confused.
Does the bolt just pass though the floor and bolt to the frame or what?

What's the best way to fix this?

 

ahh i hate rust just stick some duct tape on it

 

Search Pirate with

Little more than what you describe so check what your other body mounts look like and duplicate. Most are simple triangle braces with body mount cups. Cut out the cancer and replace.

 

I did a bit of searching Brian.

I think I'm going to cut all the rust out, replace the sheet metal and then use 2 washers (one top, one bottom) to become the new mount. Should hold up the body I think.

The passenger side rear mount will need to be rebuilt too.
The rest are fine.

 

x 2 on the cutting of da CANCER! Also for a "sealer" you could use some Hurculiner it is some good stuff.

 

I plan to use a Herculiner but for a seam sealer I'll be using PL Premium. It's some good ish.

What gauge metal should I use, I'm thinking anything from 8-10 gauge should be good.

 

I had/ have the same problems in my 82. But they are the front ones. I just cut out and got some sheet and made patches and now I just need to tack it in this weekend. I would highly recomend removing the sound deadner in the front and checking them. On the passenger side the truck had holes drilled for pedals as does the drivers side and they were rusted out under the rubber crap. Just my 2 cents

 

I have no carpets or rubber crap in my truck.
Fronts are still good.

 

You are very lucky then. Good luck on your patching