Originally Posted by Doohickie

I have a data point: I have a 1966 Raleigh DL-1 Tourist that came with what I believe to be the original B72 saddle. The leather tore, so I replaced it with a new B72. There are several obvious design changes.
. slightly shorter and narrower
. rails are black instead of chrome
. construction consisting of two pieces of leather: The top piece is the traditional, skirted, saddle top. The bottom piece is a structural doubler of approximately the same shape of the top piece with the skirts removed.

I think the last difference is why older Brooks saddles are so durable. Besides the top leather, there is a second piece of leather underneath to help bear the load.