I spent several hours looking into this situation. The only thing I can figure is that there are two types. One is 3.75" center to center and the other is 4.25". I messaged several vendors and the only one that messaged me back and actually took the time to measure it for me got the sale. Anchor 2513 measures 4.25". The one I returned, although it referenced Anchor 2513 in the auction and it was stamped 2513 made in the USA this one was 3.75" and slightly offset. Both mentions the GM 9767699. I also saw 3 different Anchor 2513, 1 made in Thailand, 1 in China and 1 in India....
Scratching my head on this one.....