Spigot bushes are a small bushing which presses into the end of the crankshaft. The nose of the gearbox input shaft then runs inside this bush. You'll know when you need this bush due to a terrible racket it makes whenever the engine is spinning and the gearbox input shaft is not spinning or is spinning at a differnet speed. For this to happen the clutch must be depressed or slipping. I have found it can be made to playup abit when the engine is idling, the clutch is in and you start selecting gears at random. When its really bad, you won't be able to stop the noise with the clutch thrown out.

I buy mine for about $10 from Carters Clutch at East Maitland NSW. He usually has them in stock.

Getting the old bush out is tricky. Some people fill the crankshaft cavity with grease then get a snug fitting bolt in the bush (about 10mm diameter). Then they wack it with a hammer to create enormous hydraulic pressure which then pushes the spigot bush out. I've tried this and never been successful. We normally carefully cut a slot in the bush with a hacksaw blade then use a flat blade to remove the broken bush.

Good luck.