What year B-body? Generally, a B-body housing can be used in a A-body by simply relocating the spring perches and using a different wheel backspacing.
My '69 Dart came with a B-body housing when I bought it from the previous owner. I'm simply going to have it narrowed so I can use it with the Centerline wheels I already have and 275-series tires. I like the larger 11" drum brakes on the B-body housings.
Don't throw it away - sell it if you're not going to use it.
