I have not tested a set - but the GX460 rear bumps are different from the 4Runner ones. They're significantly taller and softer. $50ea. I *think* they would be a bolt in swap, but I haven't personally tried it.
You'd want the ones for the models with air springs. I think the coil spring models are the same as the 4Runner. It's wierdly hard to find a good photo of them. But here's what they look like:
Air spring model bump stop:
vs coil spring: