I am going to replace the double cooling fans that originally came from a parted out ph1 GTI-6 (I retrofitted the whole A/C system to my ph1 S16 from that car several years ago). Removed the grille between headlights to see if I could make out the manufacturer of the fans but could spot any markings on them.

Servicebox lists tho different options for the setup on ph1 cars. Other is branded ECIA and the other is GATE. Also the shroud has a different part number. Here is a quick recap on the parts numbers from Servicebox:

-ECIA shroud 1308 H4
-ECIA fan motor 200w 1253 33
-ECIA fan blades 1254 67

-GATE shroud 1308 N9 (NFP)
-GATE fanmotor 200w 1253 66 (NFP)
-GATE fan blades 1254 70

Both fans with motors are available as non-original parts and quite reasonably too. Not wanting to buy the whole shroud with fans I am just curious are they interchangeable or do I need to get the same "brand-type" I had before?

The reason I am replacing both is because the other one is failing - it wobbles around at full speed and makes a horrible noise. Replacing both now saves hassle from the future and I don't need to worry about them for the next 10-15 years as I plan to keep the car forever.

Yes I have access to Servicebox as I've been trusted by certain people to personally use their login information (to look up spare parts) due to a few decades of high-trust relationship being a customer of them.

Still back on the topic, I am kinda in a hurry with this thing as the other fan is failing quick. Is there any way to quickly tell the two brands apart / are they interchangeable.

I don't know the vin of the gti-6 the parts came from so I can't look it up from the sbox and I guess the filtering wouldnt even work on an older car like it was.

After diving into the non-original parts suppliers catalogs and going back and forth between Servicebox and them I also noticed that some suppliers supply a 120w motor for the double fan setup and the OE-number correlates back to both the 200w ph1 (both ecia and gate) and also to a 120w motor used with double fans on "restyl" aka ph2 and ph3 on most the models with double fans. Even late diesels and models with aircon.

Anyone have an idea why they moved over to having a "low-power" fan-motor with the later models as with ph1 there were even 310w motors used (x2!) on diesels.

What I mean here is that if I check the catalogs for a 200w fan motor it turns around to the 120w.