First, jack the axel to the frame to find where it'll hit so you know where to place your notch. If it's a CPP notch, the instructions aren't always dead on.
Then, I made a cardboard template:
Marked the frame:
Cut...and don't forget to trim some of the spring reinforcing plate so your notch sits flush.:
Refit, mark holes, spend half the day drilling said holes...paint.
and bolt on!
Enjoy!...Actual results may vary.
and don't forget about tool safety!