Darlin it ain't the block that is giving you problems! It is the HEAD. Past owners may have installed a different year model head. Look up the head numbers.
The early heads had covers that were attached thru the cover top and into the bridges on the rockers.
You just MAY have an early head that takes a TIN cover.
Look at the gasket surface on the head itself and see what the shape of the gasket HAS TO BE. Then go to the parts house and look at the various gaskets they have to offer for ALL YEARS.. get the one (ones) you think might fit and take em to the head.. The one that fits is the year cover you need.
Jeep did not do us any favors with all the damn head covers they made.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />