I have a '66 Belair.
When I bought the car it had engine plates instead of motor mounts.
I want to go back to motor mounts but I can't locate any brackets for the frame.
I see Chevelle brackets.......will these work? Can they be made to work.
By looking at the part number for any given part: even though you know they no longer sell these parts new, and these Chevrolet part numbers are no longer valid, it does tell you if two parts are the same.
So if the frame stand left and right for the Chevelle is the same number (left and right) for your '66 Impala, then it is the same part, and it will interchange. If they differ you now know there is a difference between the two parts (it could be dimensional and it won't fit; or it could be just an added hole drilled in a part for a clutch return spring distinguishes the two different part numbers).
If you are going to be restoring your car you will need ALL of the original manuals. Frequently all but the parts manual are included in one CD for a very low price (generally $25-$30), but I prefer to buy each individual manual printed and bound in the original paper back. Here is an example of a printed one: