I have a Falcon ED Ambulance 6cyl.

I use it to pull a trailer weighing 2 tonne.

I wish to increase the torque at normal highway speeds.

I was looking at a Crow 222002 cam. However, it appears that Crow only develop their cams on a theoretical basis and cannot provide any details on the difference these cams make on actual performance.

Does anyone have experience with this cam or any other mods that improved torque in the lower rev ranges

I ran a Jim Mock DEV3HL Crow 222 and then Jim Mock DEV5 in my AU. The DEV3HL is probably what you want. The Crow was good 3,500 to 4,500 RPM nice big rush but was more cammy than the DEV5 which went well from 3,500 to 5,000. Difficult to know for sure as lots of other mods included too of course.