While trying to purchase a replacement, Fast Lane and some other sites show two different P/N's for this 1990, 190E 2.6 visco clutch depending on engine series.

********, whom I've been using for parts in the past, only shows one part number (better price). I would like to buy from them unless unadvisable for some reason.

Also, Fast Lane is advising that three OEM nuts are needed for install if engine is within specific range.

Any guidance out there?