Now I understand. Yeah the 231 is a 1310. The 9 inch should/could be a 1310. Are you able to measure the yoke? Measure from the mounting points on each side. A lot of 9s are 1310 or 1330. Width is the same, but the 1330 diameter is like a 1350. I am sure someone can help more, but I would put a 1310 in there and bolt it down. If there is any movement, that is bad!
The above poster is correct. Depending on what year vehicle that 9 inch came out of it could be a 1310 or a 1330. My old 79 Ford bronco had a 1330 on it, i know that 78 broncos had 1310s. Go down to advanceautoparts or whatever is out by you, buy one of each and see which works, return the other, they are cheap, so it shouldn't break the bank.
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