Yes. The diameter of the radiator hose ID on your top housing. My ID is a tad less than 1-1/4 inches the very same as the 235 housing. Both of my examples are like that. Thanks and always happy to give you credit. Take a look at the Casting numbers page on my site. (last sentence)
I want to eventually talk to you when you have time about that page as well. I spent several hours the other day working with all of the GM Heritage site literature for each year to compile the last two digit decipher for the engine serial numbers. Your expertise in getting this page as complete as possible would be invaluable.
