James,
It sounds like you do have the newer style pump. I'm not sure of the MB numbers on the smaller pump, but the Bosch number (imprinted on the top of the pump body) is 0442201002--the larger pumps are 0442200007--there are several variants of this as well. The two pumps differ greatly in their appearance and functioning--the old pump uses a mechanical sealing system to seal the main motor body from the pump section with the main armature shaft running through two small ball bearings--metric sizes 626zz and 627zz. The newer pump has no ball bearings and because it is a "wet" pump i.e. the aramture and brushes (the motor section) are immersed in the fuel, it has no complicated sealing system like the larger pump. What really kills these pumps is dirty fuel and varnish build up over years of use. What happens is the varnish and impurities get under the mechanical seal and cause leakage. Also, because the brushes are not constantly being "cleaned" by flowing fuel as in the newer pumps, carbon dust has a tendency to clog up the ball bearings. That being said, the larger pumps are extremely reliable when care is taken to ensure clean fuel and that the car does not sit idle for extended periods. These pumps can be successfully rebuilt with a minimum number of parts provided the main seal is not damaged. The main reason to rebuild is to maintain originality of the earlier cars, so the original shield and brackets will still fit, and I've also heard the pump pressures on the smaller pump are slightly lower and this may cause some FI problems on some cars like the 300s and 600s. The SLS site has a good illustration of the two different pumps and Naj has pointed out correctly how the pump mounts.
George Des