Need Information. What trans?

I have a transmission that came with a car I bought. I know it's a 3 speed auto with OD and is hydrolically operated. I was told I can bolt it up to my 340 although the tail shaft is a little longer. I think it's late 70's. The number on the bellhousing is 238-2 but I can't find any information on it. Are there any sites I can go to for the model of this trans. Thanks