Why would the put it there?
 

I am trying to work out why MB would on the 5L 126 place the cranking motor on the rt side along with the exhaust and most of the stearing gear. If I ever get the top bolt free I may have to rebuild the starter in the confines of the engine compartment since I am not sure how to extract the old and get the new one into position. But, I have had the time to find all of leaks as various fluids drop on my face. Actually I really would never think of anything other than one of these great old cars.

Sometimes working from further back with ~ 3 ft. of extensions and a socket swivel does the trick on the top bolt. The old starter will usually drop through if you move the steering side to side to find an opening.

500 sel starter
 

Thanks, a few feet of extention , a turn of the steering wheel and the starter "almost fell out" .