[Massive Type IV]

All the Outside diameters of the Porsche fans are the same except the very new units. any 901 or 930 part numbered fan ring will fit.

There is a great deal of variation in the alternator/fan/housing interchange as the depth of the housing changed to accomodate larger alternators in the later years. There are 3 main alternator sizes, 35,55,75 and 90 amps and the each have thir own housings. The housings are not interchangeable, however I can machine the earlier rings to fit a later alternator. I suggest that you NEVER buy individual pieces, only 100% complete housings with a complete alternator and fan, all compatible. I have had to klearn this over the years, as well as other tricks. Even the drive ratio changes, as the later cars have a smaller top pulley than the earluier years, even with the 11 blade fan on both units.

It never ceases to amaze me how far people will go to make something look faster than it really is................It looks like a 245HP engine, but makes maybe 80 Horses after the fan pulls its share!!! I'll shut up now.