Are you speaking of an entire rear axle assembly, gear ratios, ect? We need to know your plans before any one can make a proper suggestion.
If you after a direct swap a ford 9 inch from a pickup truck up until 1972 will bolt in. I have read several articles about the swap and as far as I understand they are a direct bolt in. Few have stated though the need for shims to restore the proper pinion angel and possible shock bracket relocation. This axle retains the stock 5 lug on 5.5 inch bolt pattern.
If you want a newer rear axle ford explorers and s10 are also a possible choice. The ford explorers come with disc brakes and are 5 bolt on 4.5 inch pattern and some are lockers. The s10s have drum brakes with a 5 lug 4.75 inch bolt circle but being as they are chevys you should have no problem finding one.
Give us more information on what you plan for this project.