In a message dated 96-06-07 17:55:32 EDT, raven@halcyon.com (Mark McCulley)
writes:

>I'm having a difficult time finding a replacement for the coolant temp 
>sensor on my '87 syncro. The VW part (025 906 041-A) doesn't fit my rig. It 
>appears that I have a slightly different thermostat housing. The standard 
>part is larger in diameter and is held in with a clip. My part screws into 
>the housing. I've talked to two dealers and one reputable shop and nobody 
>has seen this situation before. The part number on my part appears to a be 
>Bosch part number, it is 0 280 130 026. Anyone encounter this before? Any 
>idea why my syncro would be unique? One strange clue is on page 24.49 of 
>Bentley where there is a diagram of how the sensor fits into the thermostat 
>housing. It says the retaining spring is not used on syncro vehicles. This 
>implies that syncros have a different sensor and thermostat housing. But 
>everyone tells me this is not so.
>
>-Mark McCulley

Hmmm??  I don't reallt have an answer for you, but I do have a little more
data that might help you get to the root of the mystery.
A while back I replcaed the engine in my '87 Syncro with the engine from a
'90 non-Syncro 4 speed.  My original '87 Syncro engine had an aluminum
thermostat housing and a screw-in temperature sensor.  The 1990 engine had a
plastic thermostat housing and the temperature sensor with the "clip".  The
wiring connection on the sensor was different than my original also.
 Perfering aluminum to plastic and not feeling like changing the electrical
connection, I just swapped the whole t'stat housing assembly, complete with
sensor.  I figured the difference was a change between 87 and 1990, not a
Syncro / non-Syncro thing.  Maybe it's both a Syncro & a model year
difference.  

Hope this helps.

Jim Davis
87 GL Syncro
88 GL Wolfsburg