tm9-801.com

Not sure what the common sizes are on the G506.. will have to check the TMs.. can someone point out what ones are needed for the cab?

1/4inch socket bits:
http://www.vintagetrailersupply.com/Clu ... ts-578.htm

Set of 4 sizes fit all clutch head screws found on your truck. 5/16, 1/4, 3/16, and 5/32 drivers.
http://www.classicparts.com/1947-66-Clu ... fo/98-001/

5/32-inch, 3/16-inch, 1/4-inch, and 5/16-inch, all with 3/8-inch square drive
http://www.amazon.com/CTA-Tools-8755-Cl ... B007RKOBOM

Complete set for about $10
http://www.mcmaster.com/#clutch-head-sc ... ts/=j4anyd

Found this:

http://www.skywaytools.com/Clutchhead.html

All of the forties and fifties Chevy and GMC trucks have a special type of screw/bolt called a clutch head. When you are working on disassembling the bed of your truck you need the larger 5/16" clutch head screwdriver. When you are working in the cab all of the dash, doors and striker plates require clutch head screwdrivers - from 5/32" to 5/16".

If you try to take one these out with a regular standard screwdriver it just won't work. You will strip out the head and this screws up a good project.

The five piece set includes a magnetic handle and four bits: 5/32", 3/16", 1/4", and 5/16". This set will do anything related to clutchead on a Chevy or GMC trucks. We have also noticed that people who are working on Corvettes need these screwdrivers. Do you know about any other types of cars that require these clutch heads? Let us know and we'll add it in to our page.

The method of clutch-head screw removal that has worked best for me is to use screwdriver tips in a cordless screwdriver/drill. Set the clutch to a nice low setting, so that the driver acts sort of like a hammer drill. Use a liberal amount of your favorite penetrating oil (P.B. Blaster, Kroil, etc) and let the driver work the screw loose. DON'T use brute force, as you'll either strip out the screw head, or shear it off.