With help from friends, and a fair deal of speed reading, I now know exactly the unit sign that should be on my truck. If you recall, I want to restore this vehicle with the signs of 29/46 Infantry Btn, and the vehicle number will be my Father's service number.
Late last night (or possibly early this morning), I had finally discovered the unit sign should be:
29-46
----- (one solid line)
56
with a solid red background.

When I first discovered this, it occured to me that this seemed vaguely familiar for some reason. I started searching where I had seen this before, and came across the photo above which shows the men of 29/46 Btn on parade, being reviewed by the Duke of Gloucester! In the background is the precise sign I had been searching for. I didn't realise this was same as that on their vehicles. I thought it meant there were two groups present on parade, 29/46 & 56 Btns. Wrong!

As planned, A4 size labels were purchased this morning and I had the shop print a few copies of the Division sign onto label stock. Tomorrow I will spray a matt black patch, and attempt to copy this sign, as a stencil to the nose panel on R) side.
Hopefully all will go well!