They were cast iron. That was the only truely leagal ones back then but Jenkings, Stahl and few other pulled strings to get trhe aluminum case one "leagalized".
The storey/rumor was that NASCAR required some number of cars to be factory built for street use. I heard from 50 to 500 take your pick. They did exist. Most "originals" were dealer created however. If you had the $$$ you could just go in and they would put one together for you. Fillout the paperwork and it was yours. Showroom over the counter stock. haha
The '57 had a round shifter boot with an offset hole for the lever and chrome mounting ring. Actually I replaced it with a '58 one when it ripped which was strangely exactly the same. go Figure. The factory shift lever was bent far forward to clear the seat. Kinda like the "less" (<) than sign with short tail. This too was very similar to the '58 one but not exactly. The shifter was a 'vette with the special lever. It was a major POS. The selector pin was a 1/4 in dowel pin and soft at that. It would shear off at the slightest miss shift. We replaced it with a hardened one but it still wasn't any good. I redid the whole lever assembly and used only the bent part untill Hurst came out with the 4spd shifter.
The 57 car had a script "Fuel Injection" emblem on the front fenders. I've only ever seen one like it since on a sedan and the guy said it was an "original" I've only seen 1 'vette with the script FI and it went for over 100k at auction. The replacement FI emblem was block text and has been for a long time.
The FI for the 283 hp had larger nozzels and there were a couple others available over the counter. They were very hard to come by even back then. I had sets of all that were available but I paid dearly for them back then.
I don't know if there were ever any real original Bel Air 4psd. They did offer the FI across the board and they were relatively common with a 3 spd. As far as I know only the 150 came with a 4spd and 283 hp. Nascar version.
There is one that runs around with a GM Performance display but I haven't been able to get close enough to ask questions the couple times I've seen it. It's a 150 black and white. Looks like barn paint.
