Please forgive me but I forgot to mention the size of the 1.6 rockers. They are 1.6 3/8 self aligning roller tip rockers.
this can be used for the non adjustable and the adjustable rocker setup. when used with the non adjustable (vortec) setup , it will be a direct swap, just get some new metric rocker balls from RockAuto or reuse the ones from the origanal rockers providing wear is at a minumum!!!
The full roller rocker has a roller trunion and a roller tip and can only be used with a adjustable setup! You can convert to adjustable by just buying new rocker studs (Vortec) From ARP or Summit.
Remember that both of these setups will have to be self aligning! If you go with regular rockers you will have to purchase guide plates!
One more thing with Rockers. If you plan on using your Blazer as a daily driver stay away from aluminum rockers! They sound good and are very pretty but steele is the key to durability! There are a few companies that make steele rockers that are way stronger than aluminum and are lighter where it counts , over the valve.
But if you plan and will remove your rocker covers to inspect the rockers go right ahead and use aluminum. Just try to check them at least once a week!