One difference on the automatic transmission is the type of torque converter. The 230 and 250 had an aluminum converter that had a bit of a tendency to leak at the rivet joints. From what my mechanic told me, the leaks are extremely difficult (close to impossible) to repair. On the rebuild of my transmission he installed a later type, steel with a welded joint (at the input shaft).
I know there are also differences with the bolt pattern on the converter itself. Mine required six bolts. These are on the converter itself, and are in groups of two spaced around the edge of the converter (there are two bolts at what would be the points of an equilateral triangle).