Universal Carrier track adjustment

[Eric Szalanda]

Happy new year all.
I am moving my UC mortar carrier around ( using my F15a to push and drag it) and I want to loosen the tracks to make it easier on my old truck. I need to know what size the nuts are on the track adjusting plate. They are smaller than on my LP2A. I have a large solid tube spanner for the LP2, but it doesn't have a size on it. I guess that it is probably a BSW size, being British. I can measure for a metric size, but I would rather try to get the correct size.
If anyone has a picture of an original UC tool, ttat would be good too, as I will know what to look for.

regards

Eric Szalanda