My 628 was produced in late 83 so it on the E28 platform.
Got this from
www.bigcoupe.com and thot you might find it interesting.....
" A brief history of the E-24 6-series coupe
A high-end two-door luxury sports coupe dubbed the 'Bavarian Ferrari,' the 6-series is considered by many to be the most aesthetically pleasing BMW of all time. Just 86,219 units were built between November 1975 and April 1989. About half of those came to the United States.
During it's production, many changes were made internally and externally,though to the untrained eye, the outward appearance of the E-24 coupe remained constant.
Initially the bodies were based on the E-12 5-series platform, the earliest being built at the Karman factory and shipped by train to BMW for assembly. This quickly became a problem and by 1977 everything was done in Munich. The original 630CS was carbureted and had a 4-speed gear box which remained until 1978 when the 5-speed replaced it.
1979 brought the end of the non-injected fuel system and indtrodued the first computer management system. Also available at this time was the 'economy' version 628 CSi and the introduction of the ABS braking system as an option.
The E-12 platform remained until mid-1982 when the change to the E-28 5-series platform was indroduced. With a much improved suspension, engine, interior and a computer-based engine management system, the new 6-series also got subtle body changes: the front fender flairs were increased and the antenna moved from driver's front fender to passenger rear.
A 4-speed automatic was an option in 1983 and this was also the last year of production of the 633 CSi.
The ///M cars were first introduced in 1984, available only in the European models. It wouldn't be until 1987 that a US version M6 was produced for the American market. Also in 1984 airdams became standard equipment with recessed, rectangular fog lamps.
1987 was the only year for the US-specific L6 model. A 'luxury' 6-series that had all leather interior including headliner and dashpad, rear A/C with cooler and was available only as an automatic.
In 1988, the world-wide bumpers replaced the euo and US bumpers and made all the cars look the same. Airdams now had flush curve-edged fog lights as well.
April 6, 1989, the last E-24 coupe rolled off the assembly line.
During it's production, there were several 'specialty' models built. German tuners Alpina, Hartge, and Schintzer made high-performance models adding their own engine parts, suspension, wheels, interiors and more. Some of these were turbo-charged.
In addition, many dealers offered a convertible conversion as an option at purchase (or after) and though there is no number as to how many of these were made, several still survive."