I think they all are including 261's but not the 216's . I had a 235 in my 50 and swap in a 261 and used the 235 intake. Hope that helps.
It depends on what the engine is in. As far as bolting to the intake ports in the head and to the exhaust manifold, all '50-'62 235 and 261 intakes should interchange. If the 235 is in a '61-'62 Chevy car, the stock intakes were lower for additional hood clearance, and an early intake may get you into problems with the hood.
Thanks,The motor in my Suburban is an early pre 50 low pressure 235. It was just rebuilt prior to me getting the truck and it runs like a top. Hood clearance is definitely not an issue. I just want to make sure it will bolt up to the motor correctly. Thanks again.