The first few years 70-73 they used a closed loop swingarm. In 74 when they did many frame mods the changed to an open ended swing arm. On the later models, 81, they went back to a closed loop.
I went and snagged pics from boats.net.
#1 is the 70-73, #2 is 74 to 80, #3 is 81 up.
In pic #2 part 10 is the tee shaped block held in by bolt 11. You can remove bolt 11 and pull the axle, adjusters and the wheel together. On your disc brake you can pull the caliper off the bracket by removing the bolt at the bottom of the caliper. This way it won't disturb the brake, you leave the line hooked up. Just hang it up out of the way. On the bracket you will need to unhook one end of the strut.
This will get the wheel out but you will still have the axle stuck. It will give you more room to work, and you can get the wheel up on the bench where it's easier to work with.
Leo