727 trans

Hey guys I need your help. I picked up a 360 with tranny from a 78 diplomat
my problem is I cannot tell what size the tranny is. The #'s I found on driver side of housing are PK4028815 5904 341. I have looked at numerous sites and several threads and have come up with nothing. I was told it was a (a727), hopefully that is correct. Can anyone help with my odd dilema? Many thanks and lots of appreciation.