there are different sets, just buy whichever lists the ones you need. I bought the basic + expansion set and have used most of them over the years.
M8 bolt you'll need the 13mm grip nut, unless it's really far gone, then 1/2" might work.
used them on a number of things and they are very good, but not ideal for confined spaces since you need to put them on absolutely square and put them on with a fair bit of pressure (or tap on with mallet carefully) to get them started.