I have a 2003 Tacoma 4x4 Double Cab. I bought some OME 883 coils and OME 90004 front shocks from Toytech in Feb 2010, had them installed by my local mechanic. Truck had 76K miles on it at the time of install. It gradually developed an ever-increasing squeak in the front end (which I isolated to be coming from the top shock mount). I had it in the shop a couple times to have the problem looked at, but all they did was tighten the top nut and lube the top bushing (which was new). After that didn't fix it I took it back again (87K miles) and they disassembled the entire assembly and this is what they found: the shock piston was worn and the hole in the top plate was also worn from excess play. A call to tech support at ARB determined that this is not an uncommon problem encounter: "It's caused by lack of preload on the shock bushings allowing the shock to work against the top plate. Either installation related or excessive wear of the bushings will cause this."
I remember seeing a similar post (with photos) a while back when I was searching for the possible source of this squeak, but cannot locate it now. Maybe this will help others if you have a metal on metal, high-pitched squeak coming from your front shocks.