I had to get dealer w/s authorized from Travelers earlier this week as the Mercedes we were to replace the w/s in had a rain sensor well they said many aftermarket sensors work after much todo they ok'd the dealer glass which in the long run was cheaper as no sensor had to be ordered! The next day we had an older S-Class FW2039 well as I called Commerce the adjuster from them had no problem with using the dealer w/s even though dealer was over $250. more
he had done a study and found to be true that most aftermarket sensors do not work and they known this and instead of ticking off one of their insureds install the dealer one! To bad most ins.co. did not do this! I have reused many domestic sensors but on any Mercedes or BMW we use the factory glass only most of the time it is a hassle to get the dealer w/s approved but can usually get the co. to approved by the co.and not the agents! Keep on fighting!
Rick

Rick ** and travelers pays HELLA quick even if you have them cut you a check!!