I had a machinist look at a good bushing in my collection and he determined it was 1 5/16" (1.3125") outside diameter with 14 TPI. He did remark that the 14TPI wasn't a perfect fit likely due to the time period it was made but he compared with both metric and standard thread gauges. This is in line with Mike and also Jack Bell's table where he describes the bushing as having a 1 1/3" (1.333") outside diameter with 14TPI.