No, the current Marbles sight is NOT just like the earlier ones. In fact I don't like them personally, and take them off any guns I buy that have one. They are windage adjustable, but I feel they are "flimsy" compared to the earlier sights. I've got a couple pages of common tang and receiver sights in my book, but there are more types that show up that are very uncommon.

The Lyman 29 1/2 and 30 1/2 sights are probably the best early tang sights, the Lyman 1A/2A and Marbles S1 are the most common.

Sometimes just lowering your rear sight all the way with the elevator is enough to use the tang sight. Other times it's necessary to remove the rear sight and put in a sight slot blank, or a folding rear sight of the appropriate height.