any offroad store should sell the brackets you need. i think modern has them in stock. i got some (complete with hooks) from the auto wrecker a few years ago.....
just an FYI you cannot mount tow hooks to a ZJ cheap..... if you just drill two holes and bolt in teh tow hook it WILL rip out. the factory stock tow points are a bracket in a kind of 'L" with a big bolt plate that bolts into teh side of the 'framerail' and is sandwiched by another bolt plate on teh other side, and there is an extension which bolts into the radiator support