you have to be careful with the struts, don't just replace with anything, they need to be rated for the weight of the door plus whatever spare tyre you have hanging off it.
I had some made for my hardtop as I couldn't find any off the shelf due to the ends that you need and a new, genuine one from the Suzistore was quoted at $120. mine are a bit too strong though and push the door open too quick so you have to hang onto it!! but in saying that, with the 31" Mud tyre mounted on the door, it doesn't move in the wind and stays open on any angle.
if you have a company close by such as Universal Engineer Supplies (
http://uesint.com/locations/ ), take your old one in and they can make one up/have one made to suit, mine cost about $25 each ( bought 2, 1 as a spare ).
the part number is got supplied from UES is UES600N-460 but like I said, it's a bit too strong.