603 589 00 40 00 "fan counter holder"
 

These tools seem a bit spendy. Can somebody post the basic dimensions
of the working end (thickness & width of two curved pieces, gap
between them, approximate curvature radius). Seems like
a quick lathe job to make one.

Geoffrey

I assume this is for holding the pulley so you can unbolt the fan from what kind of car, please? I bought a simple, inexpensive tool from Harbor Freight -- less than ten dollars (see below). You can also remove the serpentine belt and use it as a "strap wrench." Clamp it tight with a vice-grip pliers.

Pulley Spinning Tool Item # 66385 Sale: $7.99

or

Serpentine Belt Tool Kit Item # 66344 Sale: $15.99

pulley spinning tool
 

That's great. The "pulley spinning tool" looks perfect

Geoffrey

1986 250D 5-speed