Centerline Auto Drag 15x8.5

Just some info.... the vintage centerline auto drag that were 8 1/2x15 came in only two backspace, 3.31 (3 5/16) or 4 7/8.
I have a pair on my car now, but I'm not interested in selling. They are double drilled and fit my 62 savoy and my 67 barracuda.
What backspace are you using on your car? The 3. 5/16 or 4 7/8? Would you have a picture on the Barracuda? Thanks again!