Unless IÆm mistaken, the purpose of the bridges (besides the ones that hold down the cover on mine) is to insure alignment of the rocker arms. If you take them out be darn careful not to misalign the rockers when tightening the bolts. They are not there just to be aggravating!

To answer the original question, here is a link to a page that explains AMC engine build date codes.
web page <img src="/forums/images/graemlins/cheers.gif" alt="" />

Freedom Off Road