Hello Dan,
I believe they are the same in function and appearance. The early units were taged GA230SL-E and the later GA280SE both were the K4A 025 units. The only difference seems to be a slight difference in internal working pressure 2.6 as opposed to 3.2. The books show a slight difference in the flyweights of the governor. Many of the early W108 sedans and finbacks also used this unit up until May 1969 when the sedans were changed to the newer design. As you probably know, the W113 used the older K4 025 until the end of their production.
Now I cannot remember if the bolt configuration of the converter/flywheel connection are the same? Seems like one has four bolts and the other has six?
Joe Alexander
Blacklick, Ohio