to softconsult steve: your post is of absolutely no help. nobody posts here to get spanked by you or taught a lesson. you have nothing helpful to offer!

to Ron:I went to my local benz dealer for the harness. the vin was of no help. they would only go by the part number off the old harness. however, you are correct that if they give you a wrong harness they will swap it for the correct one without further charge.

to deanyel: the part number off the old part is good...if you can get it. my old harness had the part number printed on a white shiny plastic tape strip wrapped around the lead wire. it was dirty so I tried to clean it, the numbers got totally smudged and wiped off. there is no other visible place on the harness showing the part number. it may be located in alternate places but you can't see that without removing the harness. not a good idea since replacing the harness is must easier if you lay the new one over the old one are swap plug by plug. pulling out the entire old harness leaves you with 24 or 26 plugs to guess at where they go.

If you got the wrong harness (you are stuck with it) there is only one other alternative harness that could work. by elimination they should know what the correct one is. talk to them, they should work with you. another sure way to check is meticulously trace the existing harness in your car and count how many plugs come off it. the count should either be 24 or 26. that count will definitely tell them which harness you have. as for your mechanic, it should take about 1 to 1.5 hours to swap harness. at worst it will cost you a couple hours of his labor. you don't mention why your mechanic said the wiring harness had to be changed. was there a check engine light that came on or is your mechanic noticing crumbling wire insulation.