M2M is correct re the 26-27. I ran my huckster for many years with just the rears installed (small drum), they really did help esp when going over speed bumps and around corners. It now has a larger drum rear end, I don't have any installed now and she is a bouncer.
While it might be over kill, if you have small drum pre 26, you might think about the double type on the rear. I did not see the need for them on the front, not as much bounce up there as on the rear. Cool factor they look the part, but my OP is not needed.