Truck tool boxes

So I'm thinking of building a tool box for the back of a truck, (70 dodge D250) and I'm looking for ideas. I will need the doors to open from inside the truck bed because I tried a side opening tool box and I'm way too short to get anything from the side of the truck.

I'm trying to outfit a general service truck for yard use and just being handy but not like a shop on wheels or anything too involved.
Any ideas?