Matching numbers, or in this case engine numbers, are kind of like " classic cars." It's a thing that has certain meaning but has been locked on to by the car collecting crowd. On cars that can be cloned, which are rare and valuable, it means everything, that, or they're million+ cars and those things do matter. On our 113's, options aside from model, condition, year, and perhaps colour, would be one of the few things that make one car worth more than another, all other things being equal.
Given the fact MB dealers were instructed to stamp the original engine number into a new replacement block, what does matching numbers mean to a mass produced fairly common car? Is it nice to have? Sure. Is it going to bring you more at auction?
( Roll MS in 3....2....1 )