drywallstuds
I am trying to figure out when a wall was installed. I am certain it was not original to the house since the wood color does not match many of the other studs and there are left overs of an older wall behind this one.
Are there markings on studs or drywall that could indicate when it was made?
It is not safe to simply cut a hole in the studs, and while the safe probably would transfer the load, you do not know that the safe was designed to transfer vertical loads, or how it will react. The consequences of a mistake here could be severe long term.
Therefore the proper course of action is to reframe the wall. Generally you would do this by adding a lintel (a RIGID horizontal beam that spans an opening typically over a window or door) at the top and bottom of the wall wide enough to transfer load to either side of the existing column, and then add new columns on either side of the existing post to carry that now transferred load down to the floor lintel and thus to the underlying support.
The air gap problem is quite common: The sheetrock on many walls I have encountered doesn't contact the studs everywhere. So, when you tighten down a TV mount to the wall, the drywall deflects toward the studs. You can easily cause cracking of the drywall, particularly when there is a seam in the area.
The principle of the solutions in this case make use of a fastener's ability to support an overhung load.
The fastener and the building structure have to be strong enough to withstand the torque created by the downward force of TV and Mount acting over the distance between the drywall surface and the building structure.
Assuming you find wood building structure in there (furring doesn't count here because it will twist under the torque), I recommend hanger bolts.
Use a spade bit to clear a hole in the drywall big enough to accommodate a nut flush with the surface of the drywall. Then put the mount over the hanger bolt and tighten another nut down on that. The first nut will keep the drywall from deflecting toward the wall. Size the hanger bolt larger than normal because of the overhung load. From your description I would guess that 4x 1/4" hanger bolts would be adequate.
Make sure you pilot drill for your hanger bolt or you risk splitting whatever wooden structure you're screwing into.
I've also encountered furred out concrete clad in drywall (common in highrise condominiums). In that case, the same principal as Case 1.1 applies, but use "drop-in anchors" and a threaded stud instead of hanger bolts.
Sometimes drywall is attached to and is in contact with (i.e. no air gap) furring.
Where furring is attached directly to the building structure, drive multiple wood screws directly into the furring. If there is some hard material behind the furring, ensure that the screws are short enough. Otherwise they can jack the furring from the building structure when their points impact cinderblock or concrete.
The principle of this solution is to transfer the load to the building's structure directly through the furring.
Where furring and drywall are creating their own structure, drive multiple wood screws into the furring to fasten your TV mount.
The principle of this solution is to use the furring to distribute the load to a large area of the composite structure of furring and drywall.
Drywall itself is rather heavy, so if the wall is able to hold itself up, there's a good chance it can hold up your TV to provided you distribute the load over a large enough area of drywall and furring.
Best Answer
Sometimes there is a date of manufacture printed on the backside of drywall. Old ink on brown paper may be hard to see.
The modern stuff is not infrequently dated to the second, presumably for quality control, as it spews off the line.