Hi Chris, welcome to the forum.
Hopefully you will be able to find your ARN using your chassis number, there is even a very slight chance that an in service photo may exist...
The CRs are very thin on the ground these days, good to see another one coming back to life!
Are you restoring it in bronze green or olive drab?
I'm not sure about the other plate that you mention, all army vehicles of this period did have a repair plate that was attached when they were accepted from the factory, but CON S.T does not ring any bells.
This is a great forum, I find it a very helpful group of great people.
We can usually help if you get stuck with anything. (On your vehicle that is)

If you have any photos, we would love to see them.
Cheers,
Mike.