I had a little universal square tool with a 3/8 driver opening for a ratchet extension to attach to. It has several different configurations. I broke that and last time i actually just used a too used for removing pulleys or something like that. its is adjustable with two pegs on it. I bought it to hold the ac pulley while loosening the nut on my 2005 F250 so that I could remove a shim to get my ac to stay on. this tool worked great for turning my rear piston in. keep in mind that after you run it in it also compresses some more at the end by pushing in on it. I've also used a needle nose pliers but thats a slow process for sure.