Drew you have 1/2 of the equation. If there isn't a bolt on the bottom, there then should be one on the very top of the filter head, the part you call the top. Take a picture from the top. Your description of the canister doesn't help as they are all the same within the size. I am sure yours bolts on through the top. What I am trying to explain is when you look down on your present set up, right in the middle of the filter head( the part that bolts to the block) from what you are telling me when you say there isn't a bolt on the bottom of the canister, is there is a bolt right in the middle of the filter head that goes down to the canister and is what holds the canister to the filter head. I am sure this is what you have but would really like to be sure. It only makes a difference in a minor part from me, but will save some back and forth parts exchanging