Use the same type of gas for the rear lift up tailgate. Ebay has the struts cheap enough, but make sure you get a set with steel ends as opposed to plastic ends. Obviously steel ends will be a lot stronger and more durable.
1. Remove the original bonnet assist springs. Keep the bracket that bolts to the actual bonnet. Drill out the rivet on the bracket. Re-use the top bracket, drilling an 8mm hole in it to accept the ball stud. Fit the top ball stud here with washers and nyloc nuts.
2. Drivers side - Remove the bolt from the bracket of the air cleaner housing. Bolt the other ball stud into this hole.
3. Passenger side - There is a 6mm threaded hole in almost the same position as the air cleaner housing bolt on the other side. It isn't in exactly the same spot, but it's close enough. Drill the threaded hole out to and retap an 8mm thread into it. Screw the 8mm ball stud into it using a spring washer.
Bonnet Strut Installation
This mod is pretty cool as you will get the benefit of it every time you lift the bonnet! There are a few different methods to do this.
Exactly the same as Method 1, but use 100 Series Landcruiser bonnet struts. These struts are approximately 30mm longer than 60 Series tailgate struts. The only real benefit to using these longer struts is that the bonnet will open higher. There is a downside to this though......
Using 60 Series tailgate struts and bolting the ball studs through existing 12mm holes in the body. This method is ok but fiddly to get a nut behind the body. You could also weld a nut to a mudguard washer and rivet it to the body, but this is time consuming. There is the same downside to this method as well......
Issue with Method 2 & 3
These two methods are ok and lots of people have installed bonnet struts this way. Using these methods opens the bonnet a lot higher than standard (so does Method 1, but not as much), around 135mm higher. This can cause the bonnet to hit the plastic cover on the passenger side window wiper and possibly break it. If you are ok with this, then methods 2 & 3 are fine!