[HWYSTR455]

http://www.precisionmeasure.com/fixt5.htm

http://www.advancedclutches.com/prod...t%20Tool%20Kit (may be able to adapt, flywheel/pressure plate bolt patterns are generic on GM)

Check Proform, Coleman Racing, Northern Tool, and believe it or not, dare I say, Rock & Roll has one too. You can use a dial indicator and a clutch aligment tool too to do the check, though may not be as accurate...