speedo cluster 190E versus 300E ?
 

are these the same unit? speedo cluster 190E versus 300E ?
i.e. if you take one from the 190E will it also fit into the 300E? Looks quite teh same from the front, not sure of the wirings at the back though

Both cars had mechanical speedometers and I would be inclined to think they are different. The 124 cluster is definitely different than the 201 version - not entirely sure about speedometers. I know there were a variety of maximum MPH markings across the 201 line (and presumably the 124 line as well).