Well, I did this upgrade on my car. But it does not have to be expensive. All 1990-1997 911s, 928 GTS and 968 use the same mirror. The only thing that is different is the base. So, just buy a used(under $200) set of ebay or get some aftermarket ones. Then, just buy the base form one of the big three. That's what I did.

I bought a set of used original Porsche mirrors of a 993 on ebay for under $150. Then I just got the bases from 928 international.

What's interesting is that none of the big three knew that they were the same mirrors??

Here is a picture.

 

Here is one more. They are awsome!!

 

Do the later mirrors completely cover the spots on the door that were previously occupied by the standard mirrors?

I think the PO had the car resprayed without removing the mirrors which means that there will be an ugly spot under the original mirrors.

 

Blown Beast,

Your "reuse the old motors" is the advice Dave gave me, In part because the connectors are different and the wiring is also different.

BTW, There are also detailed instructions for doing the swap on the 928 international site.

 

the flag mirror has a rectangular base , the Aero has an " ovalish " base which DOES NOT completely cover the footprint of the rectangular base . So if the door is repainted with the flag mirrors not removed there will be a visible paint line showing mostly above and in front of the new base . The flag mirrors were used on 911 and 944 as well as 928 BUT have different mounting bases to match the contour of the door skin . The Aero mirrors were also used on various Porsche cars BUT different bases . It was for a while quite popular in L A for the "bad guys" to find a parked Porsche with Aero mirrors and use an allen wrench to remove the mirrors (takes a couple minutes) then sell them at the next swap meet for $250 a set or so . E-bay has made the trip to the swap meet unnecesary . The correct 928/GTS bases for the Aero mirrors are about $50 each part 928 731 241 00 and 928 731 242 00 .