The last LA production heads that Mopar had ended in 308 They were used on production 360's from '88 or '89 through the end - 1992 I believe. The last over-the-counter OEM style heads they had ended in 576. These may have been used on the complete crate engines and there were a variety of 576 versions that were sold seperately - 1.88" valve, 2.02" valve, ported, T/A offset pushrod hole style, etc. The heads appear very similar with the most obvious difference is that the 576 heads do not have the hole under the exhaust ports for emissions.