I have an '84 528e. The ECU in the vehicle is an 0-261-200-008. I was told that most '84's have an 0-261-200-021. I want to upgrade to the later 528e ECU with the replacable chip (0-261-200-027). I know this is possible if you have the 021 ECU but I 'm not sure about swapping an 008 for an 027. Has anyone else done this or heard of it being done? Thanks for the help.