Like tmoss said they are probably stud mount rockers. The stock style pedestal, bolt down, rockers have a 5/16" hole in the middle. They also have a pedestal that goes under the trunion. The 5/16" bolt goes through trunion, through the pedestal and bolts to the head. That is why they are called pedestal mount or bolt down rockers. There really isn't a lot of adjusting that you can do with them other than shims.
If they have a 7/16" hole in the trunion then they are stud mount rockers. Stud mounts come in 3/8" and 7/16". The problem is this. If you have stock style heads, E7s, GT40Ps etc then you will have to have the heads machined for 7/16" studs to make those work.