There were pretty simple conversions. I used Evergreen Scale Models, Sheet Styrene with 2.0mm spacing V-Groove for the truck beds.
The Toyota is the smaller of the two vehicles. Each could be said to hold a squad of infantry. The Isuzu's canvas cover is a modified one from a Pegasus American 6 Ton. I just cut the back end off to fit the length of the bed. Both are pretty easy kits, but I would probably stick with the Isuzu as a primary truck transport.
For any experts on Japanese trucks, the beds are a little rudimentary in design but there are few pictures out on the internet to work off of and I opted for the wargamer's choice!
Keeping it simple