How cheap we talking? I say get them if they are a good deal. They are better than 4.10s for sure i can tell a difference between 4.10s and 4.56s.
That was always my go to spare diff a 4.56. And everybody knows i have blown up enough 5.29s and had to run a 4.56 or 4.10 to drive to work/school until i could get another 5.29 installed.
With that said 4.56s were not too bad with 37" toyos in a second gen runner with a 3.4L. Im guessing with 35s
In a pickup with a 3rz would be even better.