Reply to rax200:
Hi PhilC,
do you have any Landrover enthusiasts about, and if they have a series 1 you will be able to get one of the brake shaft that runs through the chassis and per the parts cataloge.
[attachment=65576]Screenshot_20211203-203312_Drive.jpg[/attachment]
part 24
[attachment=65577]Screenshot_20211203-203936_Drive.jpg[/attachment]
regards

The original bolts I will call Whitworth because they appear to be. I'll abbreviate that to just W.
W nut jambs on UNC bolt with less than one thread caught.
UNC nut fits sloppy loose on the W bolt.
Thread count is 11 tpi on both W and UNC.
O.D. on W bolt is slightly greater than on UNC bolt at grip, above the threaded portion.
W bolt thread appears to be slightly radiused in the bottom of the thread cut, but appears nearly sharp at the top. (?) Thread gauge sits just a little high on W bolt.
I have a 55 deg threading gauge that fits on the W thread, but just a little high because the gauge does not have the point radiused.
W nuts take a 1" wrench, close to or at the old W formula. I would like to have one of the old, large W nuts. I believe the UNC 5/8-11 nut is a 7/8 (?) wrench size.
It appears to me to probably be Whitworth but I won't say for sure until I try the fit. Thanks for input.