That looks a lot like a 12 v generator The way the back end steps down in diameter I just had the pleasure of fixing mine this last week in my 53 Someone upgraded your truck to 12 v but used the same technology to do it. You can borrow the bracket from the inline 6 that uses that same generator and the belt will line up perfect However only one bolt hole will match the block and you have to slot or drill the front hole It’s about exactly one hole diameter off Photos of my fresh $20 junk yard replacement attached
