There is a lot of wrong info in this thread, wrong numbers and wrong statements. Even your statement stating 171 820 25 26 will beep is wrong, that post goes on to say that it is obsolete and is replaced by the part number that I quote.
Do not ask for a Chrysler part number or you will pay too much for the same siren.
I used MB part number A 219 820 32 26, it worked. It needed to have a nut (8mm I think) added instead of using the stud that the Crossfire siren used. It beeped so I was happy.