My ranger was kitted out by Denni from water fed pole systems ltd. when I moved it across although I used new bolts and nuts I reused the spreader plates, just basically thick metal blocks as these went with the tank and were still in good nick. You would probably do well getting the metal and cutting and drilling it yourself as a lot of off the shelf stuff will be thin and not up to the job.
You want to use plates at the top and bottom really if you can.
I would steer well clear of the chasis. Denni who installed mine raved about putting it through the chassis and drilled into the chassis on the ranger but in actual fact you are compromising the integrity of the vehecal.
Simon.