Today I got my GD's "chain lock" changed. It was changed upon recommendation of Suzuki mechanic due to "tuc tuc" sound the chain was making as if it was loose and was brushing the chain cover. The guy recommended me to go to a Honda dealership and buy Deluxe's chain lock as it would fit the GD.
I did the same. But unfortunately, "genuine" lock wasn't available even in McLeod Road market. So I had to settle for a Taiwanese one which I bought from Makhdoom Autos.
The "tuc tuc" sound is now gone. Thank God. By the way it was changed after 22,260 km.
The reason of the annoying sound, I believe, is the crack (pointed by the arrow) visible in the pix of the old lock below: