May 2015: This type (66055000) is still available (at a price, around £25 from some suppliers but I have found one at £40!) but there are a number of others online at about £10. Some of these have a curved bottom arm, indicating that perhaps the bolt will always be square to the arm. Another has a recess so perhaps that will also be OK, but others have a straight arm so depending on the angle the two arms take up on your track-rod ends, they may or may not need modifying.
There are also so-called 'direct acting' types which has the bolt bearing down directly on the pin of the track-rod end rather than a lever action, which wouldn't have the above problem, however I've always felt the flange that fits between the TRE and the steering arm is pretty thin on that type. My scissors type has a 19mm jaw, but is much beefier, so it doesn't matter if it only grips the outer part of the steering arm eye. But the direct-acting type would need to be as snug to the pin as possible to get the greatest area of the flange under the steering arm eye to spread the load. I've measured the pin on a TRE at just under 17mm, so a 17mm one would be the one to go for, not the bigger 19 and 23mm types.