E 383 , it's a 1969 model year engine , a REPLACEMENT engine would more than likely not be stamped with the model year , and not the year prior to the one it was installed in . It was assembled on 10/16/1968 which is right inline with it's casting date , the R tells you it was built to run on regular fuel , which means it was a 290HP 2bbl equipped 383 as originally built.
