with a little time and this article you can design your own 4-link.
for this discussion we'll stick to a basic four-link where the upper two links start at the frame and converge at the top center of the rear axle. The lower two links will also run from the frame to the outer ends of the axletubes.
I didn't read the whole article. Got to this part and that was enough...
You don't want to build this. Do yourself a favor and consult a expert at building suspensions. You won't likely find any here.