OK, I'm confused. I searched up for a while, but can't figure this out. I need to replace the rear turn signal bulb for my 99 Passat variant. Sylvania specs the 7528, but why a dual filament bulb? Couldn't you use the 7506, which is a single filament, dual contact bulb that would work just fine? They both are ECE P21W, same 12V, and same 1.75 Amp. Thanks for the help...