I don't know what size hole you have on your uke but I can tell you what is required for Pegheds. Keep in mind that the shaft on the Pegheds is tapered and also threaded. There are right and left hand threads. Do not confuse them or they will wind themselves loose under string pressure. If you are using size 743A or similar, installation requires a 7 mm drill bit. I like to start a bit smaller with a 9/32" bit and ream it with a tapered reamer. I stop when the larger of the two holes (in the back of the headstock) is about 7.5mm. A small dab of Titebond on the threads make sure everything is secure yet removable if need be.
If you are not familiar with how Pegheds work, play around with the tension adjustment to become familiar with it.
