Good day. Have an older set of "slotts" for my 240Z and need center caps. My opening measures 3 1/8. Contacted Motorsports and they have a set with 3 3/16 opening (plastic material). Motorsport Rep did not know if this 1/16 inch difference would make a big difference. If they did not fit and I broke one trying to get it on - Motorsport would not accept a return on a broken part. Therefore, I will turn to the pros here: does anyone have any "educated guess" on whether these caps will work? Are caps available in "metal" instead of plastic? Or is there another place to order caps? Thanks, David Jacks Fort Worth, Texas 1972 240Z