I have some 15 inch ss1 with pontiac push on centres. Are these the same as olds rims and which centres should I use small push on or large bolt on ?

 

I have a set if 14" ssi or magnum 500 style they had the olds cap with a disk in back that was held on with three bolts i pulled the olds and put the pontiac push on pmd center cap and have them on my 66 pontiac lemans with red line tire's.
if you need olds caps we can make a deal.