72 K5 or K10 rear u bolt dimensions

[jmking9]

I'm needing the dimensions of a stock u bolt that would have been on a 1972 4wd Blazer (or K10 I think) I need to know if they were 9/16 or 5/8. And also, what length they were. All of the stock pieces from my 72 K5 are long gone. I'm ordering new stock height spring, and trying to peice all of the stock components for the rear suspension. I've got everything tracked down except for u bolts. Any help would be greatly appreciated!
This picture is for reference, and as far as I know what my setup should look like.