as in its a soft top already but l wanna board out behind the seats. any1 now the best way to do this using a wood backing covered with 3mm steel?

cut the back off

see that bit at the back of yours that a pickup doesnt have? .. cut it off.

If u mean like this.
http://suzuki.off-road.com/suzuki/data/articlestandard/suzuki/532005/277666/sj410-2.jpg

Then it woudl appear to be a factory option, u may be able to pick one up second hand somewhere which would most likley the easiest option.
Having never looked into this for a 4x4 before l can only offer my advice in relation to modifying a car to a pick up.
you would require pleanty of strengthining & bracing to stop the chassis from twisting (although with this vehicle being a soft top it may well already have enough support). You will also need to (depending on the weight u intend to cary) strengthen the rear ''cargo'' area of the car.
It will most likley reqiure LOTS of fabrication & welding so unless u r familure with welding & the processes involved in the structural workings of cars l would suggest either buying a pick up or getting the work done by a proffesional.