What is a "special chassis"?
 

My question relates to the Certificate of Authenticity we received from the previous owner. There are only two options listed; 1. "Tiptronic" 2. "Special Chassis with M393". From what I gather, the M393 has something to do with wheels. From the previous owner's description it sounded like they were Design 90's. He changed them out to the narrow spoke Cup wheels (Cup II?) (starfish?). But what the heck is a "Special Chassis"???
http://forums.pelicanparts.com/uploa...1359522058.jpg

Could it be about the unusual color?

$3,000 Option

?? 16" alloyed forged wheels, lower suspension, different front wing.

Adrian's book lists several descriptions for the option code M393 from '78-'01.

1) Forged wheel 8J x 16 and 9J x 16 [most likely for you car]
2) Rear fender decal for Turbo model
3) 17" wheels (Targa)
4) 18" Targa Look wheels (Coupe, Cabriolet, C4S). [This must be for a 993 model]

What year is your 964? Do you know if your 16" wheels are 6" and 8" or are they 8" and 9"

I'm beginning to think this may be a mistake on PCNA's end. I do have a copy of Adrian Streather's book. I've read those pertinent sections several times. If it was a Cup car it might list 'special chassis'. The 964 type code for a C2 coupe is 964330. This is also the same for a Carrera Cup. My trunk option code label does not have 393 on it. There are five other codes on it that the CoA does not have. As I stated above, the wheels on this car are not original to the car, although I believe these were available on 964's as well as 968's.

Oh, I assumed you did not have the trunk lid paper label so you ordered up a CoA to figure out options, etc. Yes, with a CoA you almost have to assume there will be a mistake. The older the Porsche the higher the likelyhood there will be a mistake.

The wheels you have on now were commonly delivered on the early 90's 964. I don't recall seeing them polished or chromed from the factory, but they certainly could have been.

Thanks Brian. As far as I understand, Porsche never chromed any alloy wheels. Only the old steel ones. Any chromed alloys were done privately. We've only owned this car since 6/11. The previous owner gave us the CoA at the time of purchase. He also said he replaced the original wheels with these. He did not like the original ones. From his description, I think they were Design 90's. I had assumed those were what the CoA refered to, but I didn't know what might be 'special' about the chassis.