Hey there;
Very nice looking truck, I really like the Green and Black paint.
I have a 46 Chev 1/2 ton that is all original drive train, down to the 6V neg ground.
I have also been considering replacing the differential gear set.
There are some good articles on the site that give you good ideas- food for thought.
You can either buy a new gear set or work out a swap.
I would be interested to hear which way you decide.
Welcome to the site,
Steve