No, they do not work! I bought a set and tried them on my 451. The pulleys have a different profile so the A/C belt tool does not fit, plus the tension thingy is not needed, as the 451 has a spring tensioner.
I bought a Lysle #59370 stretch belt tool for the A/C belt, but have tried it yet.
If anyone with a 450 wants to buy my Green Tool set, PM me...please!