The tablets are called "supplement" and are required on caddilac's. I do believe they have some stop leak properties as well. I was having a corrosion problem on my dirt bike once and used one --seemed to work pretty well. I have not put any on my vette yet as I feel if its doin ok leave it alone.
I just put a new radiator in my 96 and obviously in the process changed the coolant....put six of these tablets in there as they are also recommended for the vette !!....some tips when/if you do it:
Six tablets is a lot of solid material to put in a cooling system. The recommendation and what I did is to first crush the tablets into powder (leave them in the original package of six and whack 'em good with a hammer, the package wil hold up and theya re almost all powder after that). Then I pre-mixed them with coolant, about 2 pints at least and poured this muddy (!) suspension directly into the radiator (recommended by GM !!). Otherwise you'll never get the recommended six tablets into the system. This worked very well and I have no prob's..