Differential and drive shaft questions

Yes that looks like the 8 1/4 axle. They are stronger than the 7 1/4 and are coming up in price as well. You will need that with a 360 engine.
Thank you! I am not keen on distinguishing parts (I read thru forums here to learn, but ... advice from veteran members is best.) Will there be a tag to confirm? The car appears to have been partially buried (even the engine has soil/dirt) so I'll be scraping and brushing stuff off ... just to know where to check for a tag/number/code.