if this is a 4wd frame that already has the hole, you can stack two hole saws together on the same arbor using the inner hole saw as the guide and the outer your new hole size.
nah, we really don't. Back in the day we had a piece we did that was for locating the new hole but it wasn't a strong seller. Pretty straight forward to do some measuring, hit it with a center punch and use a good sharp pilot bit.
OH, and go through with the pilot bit without the hole saw then put your hole saw on and finish it out. Lot less chance of braking the pilot bit.
FYI. Get a good hole saw. I spent 45 minutes with a HF one, and didn't get through one side. Went a picked a a "diablo" carbide tipped saw (Milwaukee brand) from Home Depot and had both holes cut less than three minutes later.
PicsI have a complete Milwaukee hole saw kit.
To open up the spring hanger hole I used this double threaded arbor thing and 2 lenox hole saws, 1 the diameter of the original hole to keep things lined up perfectly and the second the diameter of the new hole to be made.
The teeth on the lenox hole saws seem to be finer/ closer together and made quick work of making the new hole.
I'll take some when I get home.Pics