The 1954 was a complete design change. It will not retrofit without the crossmember coming with it.
Here is the 54' housing/crossmember in my truck so you can see the difference. It has a large 2-piece mount on each side with a bolt going through the crossmember into the bell housing to hold them together. I can tell you this it has much less vibration than the old style mounts as found on the 51'.
https://www.flickr.com/photos/advance-design_parts_co/8129071781/in/set-72157631867396207