D0AR ? You've got the R confused, it's actually an "E". This translates to this: the block was originally designed for a 1970 full size Ford ( D0=1970) "A" stands for full size Ford, which in 70 could have been a Galaxie ( or maybe not, I think that was the year the Galaxie name plate was dropped) Custom 500, or LTD. All this means is that, that was the vehicle it was designed for, it doesn't mean that was the vehicle it was actually installed in at the factory by Ford. It could have been used in any other Ford, Lincoln, or Mercury that also used that engine size, beginning in the 1970 model year to whenever that engine block was discontinued or revised, that's what the "CJ" means, if it's the suffix after the part number ( think that's 6015 for an engine block) The first version of a part would have had an "A" there, and each time something was changed on that basic block, a new suffix would have been added. Can't tell you what the "4" stood for.