I pulled the volvo adaptor. The aluminum washer was grooved from previous use. I measured it as 1.008" id, 1.265 od, 0.065" thick. The banjo bolt is 1.000" od where the washer passes over. I'll check out napa tomorrow, but in the meantime I found on-line an place that sells various washers for crafts. There is a copper washer that is 7/8" id, 1.250" od, and 24 gauge (0.020"); there is an aluminum washer that is 7/8" id, 1.250" od, and 18 gauge (0.047"). The aluminum washer looks attractive, mostly because its thickness is greater, and I can ream it out to the 1.008" id needed. Hope to find an alternative, but there are options if I need to fab one.