Can steel taken from any car patch the rust holes in the car I have?

I have a 66 ford fairlane 500 that needs some patches. I'm trying to figure out if I can cut out of pieces from some other car to weld onto mine, and if not just any car works what cars will have the right kind of steel?

Sure, I did that back in the 70's on old rusty cars. A better solution is to buy new sheet steel, from a parts store, metal shop, or local body shop.

Replacing/patching panels depends on where they are and what shape they should have. There are many aftermarket sheet metal suppliers for whole sections (rear quarters, floor pans, roofs, etc), so for many applications it's cost effective to go that route. You could take a sample of your car's metal to a metal supplier and they could mic the gauge (probably 16 or 18 gauge on the old tank, depending) and get you some steel. I use to work at a sheet metal shop and we had various thickness steel, most was cold rolled or electro-galvanized, either would work on your car with proper prep work;have to clean the steel, and with EG you need to sand off the coating where your seams are to not produce unhealthy fumes.Since you have to sand/prep for paint anyway the cold roll is normally a better option. As jon_mac says, lots of folks would just get a junker rig and pull the metal from that, easier if the cars are same model/era at least because steel alloys used did change over the years and while it should weld up you might have minor issues with galvanic corrosion later, but nothing to worry about real world. Problem with old steel is its OLD, so you might have to prep it a little if you have rust, and I would sand/rough it up to take paint anyway before welding, plus the paint/coating on the savaged steel might not be compatible with your next paint/coating system. So, lots of options, but biggest thing is matching thickness and using steel with similar properties, some European steel had a tendency to rust faster than US stuff.

Yes you can. Newer cars use thinner metal than your 66. Hoods and trunks are good for large pieces.