When I went to pick up my car from having pipes made to hang the Ferrari mufflers, muffler guy tells me he broke the key off in the ignition. (Then has the nerve to say "I wish you had told me it was such a weak key". I resisted the urge to say "That's funny turdnugget, in the 10 years I've had the car, it was never 'weak'" ) I could turn the tumbler with the broken stub of the key, but the starter wouldn't turn. After hours of chasing my tail, I discovered he twisted the shaft on the tumbler assembly to the point that it wouldn't actuate the switch to hit the solenoid exciter contact. When I tried to straighten it, insta-snap. . . With the evidence uncovered, I'm pretty sure he went to start the car, had to hit the starter again, and didn't go back to off before trying again, just cranked harder instead. . . bend & snap.

So, I've got 3 parts cars: a 70 (which I know won't work), a 75 and a 76 that appear to have identical ignition setups. The car I'm trying to fix is a 73. The tumbler is different, but looks like the body may be similar in all the important ways to swap it into my 73. When I search for a new part for a 73, they all look like the tumbler assembly out of the 76.

Before I go to the trouble of pulling and disassembling the 76 switch, Will a 76 tumbler fit into a 73 ignition switch assembly?

I bought a '75 car without any keys - got a '73 ignition tumbler with a key and it fits perfectly ...
hope this helps

I just went ahead and took a stab, and the answer is yes, a latest model tumbler will fit in a 73 ignition housing.

I needed to make a small access hole in the side of the housing to push down the spring loaded pin at the bottom end of the housing (due to the pin being different than the tab at the same location in the 76 housing, and just a mm or 2 longer), but other than that, works just fine.