Per the technical guide...

997 GT3 Stock brakes:
Foot-actuated, hydromechanical transmission, 2- circuit brake system, brake booster, 6-piston aluminium monobloc brake callipers at front, 4-piston aluminium brake callipers at rear, per
axle distribution

350x34mm front rotors, 350x28mm rear

PCCB:
Optionally available:
enhanced carbon-fibrereinforced ceramic brake discs, internally vented and cross-drilled, 6-piston brake callipers at front and 4-piston brake callipers at rear, brake disc diameter 380 mm at front and 350 mm at rear, aluminium brake-disc chamber at front and stainless steel brake-disc chamber at rear

Even my 1992 C2 has aluminum calipers...

 

I've been told by someone at a highly credible race shop that the two different brake calipers are identical and even have the same part number at Porsche. Anyone want to weigh in on this a little more, because I am now thoroughly confused.

Thanks.

 

The standard brakes GT3/GT3RS use the same front calipers as the 996 GT3 with standard brakes: part# 996.351.431.90 (L) and 996.351.432.90.

The front calipers for the 996 GT3 with PCCB are identical to the 996 GT3 with standard brakes. However, the 996 GT3 PCCB calipers have a different part# because they are yellow.

The 997 GT3/GT3 RS front calipers with PCCB have longer bolts to attach to the uprights, and they have a 15 mm longer hole for those bolts. Part# 997.351.431.92 (L) and 997.351.432.92 (R). These calipers are yellow as well.

If you want to use the 997 GT3/GT3RS PCCB calipers, you need to upgrade to 997 Cup front rotors, or 997 GT3/GT3RS 380mm PCCB rotors.

 

Thanks for the response. I'm trying to use the regular/non-PCCB calipers from a 997 GT3 with PCCB rotors. I'm being told by the people doing it that it's no problem, but that's not what I'm hearing here and I'm trying to figure it out before I get on the brakes at the end of the front straight at Road America. I really don't want to get my answer there.

 

If you want to use your 997 GT3 standard calipers (red calipers) with PCCB, you will need to use the 996 GT3 version of the PCCB rotors for the front axle, and either 996 GT3 or 997 GT3 rear PCCB rotors.

Be aware that the 996 GT3 came with Gen I rotors. There are Gen II rotors available for the 996 GT3. The PCCB rotors on the 997 GT3 are Gen III, same construction as Gen II but improved cooling through different drilled holes pattern.

If you want to use the 997 GT3 PCCB rotors (380mm instead of standard 350mm) , you will need to change the front calipers and caliper bolts to either the 997 GT3 PCCB or the 997 Cup, or get a custom made 15mm spacer and use the longer bolts while keeping your stock calipers. In this case, you won't be able to use your original front rotors anymore.