Do your home work.

They are spacers for the "china" wall at the ends of the block. You can still get them new I believe from MP. I used silicone sealer on the bottom of them stuck them on then put the heads on. On top I bought a Magnum (either V6 or V8 will do) intake gasket set from Mopar and used the end seals out of that on top of the spacers and below the intake. They are molded rubber sandwiching steel so they hold their shape and won't blow out. Check to see how far your intake will crush them as you may need to use some silicone sealer on both sides of them as well.