At a local antiques mall recently, I found this mint condition porcelain unipart that measures out to match a U-869A (7 1/2" - 6 1/2" - 5 3/4"). It is virtually identical in glaze color to the U-869A example pictured on page 107 of Elton Gish's essential "Collector's Guide for Porcelain Insulators (Unipart Pin-Type)" (2015), but this one has blue underglaze marking that says 1981 over the letters BBC with two underlines. Unfortunately, there is no such marking listed in Elton's equally essential "Value Guide for Unipart and Multipart Porcelain Insulators" 3rd Edition (2016), although there are other listings in the value guide for items marked with BBC. So is this one here unlisted, or do I have the U-number wrong? Suggestions as to the value of this one? Any help is appreciated.