I made an m104 fan clutch holder tool with a length of 3/16" (I think) steel rod purchased at Home Depot. Used a bench vise to bend it, a hacksaw to cut. Total cost - $1.99, total time - 5 minutes.

I've not had any problem removing the 8mm allen head bolt securing the clutch to pulley using just a plain 'ol allen key. Some folks have reported using a cheater pipe on an allen key to generate enough force to break the bolt free.

The strap wrench will work just fine, but I think the tool costs more than most of the other options.

- JimY