well its just an idea , but instead of modding the ones of a 4th gen into fitting your chasis you could mod the end of each mount into supporting the 4th gen bumper , plus if is way to big you could consider that the taco bumper is smaller than 4runner plus limited flares , and the prado ( sahara or arb bull bar) is a bit bigger and people use em so i dont really see a problem on that , just a little extra protection. But yeah i would mod the previous mounts for the bumper since you already know they do fit into the chasis , while the newer ones do change since the chasis and basic structure of the 4runner did change