For the money, the best tool to buy is a drag link socket - in my estimation. If you can, get a 3/8" drive otherwise use an 1/2" adapter. They look like an oversize screwdriver bit. You may need to file it a bit to fit depending on size. Besides, it is probably the only tool that will remove the plug from your sludge trap.
Alternately, a piece of 1/8" flat steel strapping about an inch wide and 8 inches long can be made to fit. I made one so that the other end fits the clutch spring nuts and has the centre cut out so that it can straddle the bolt as it comes up through the screw head. A hole at one end to hang it up or to lever with a screwdriver along with a coat of paint and now it's a poor man's tool. Filed smooth and the coat of paint prevents abrading the slot.