You are looking for a Tractor unit - HGV prime mover.
Body can be done in Kenya. Otherwise shipping a body escalates costs.
Mercedes Actros/Axor is fine & longer lasting.
SPARE PARTS available... same way trucks are shipped. For smaller part (servicable) as well as 10-20kg weight you get them in 7 days (air freight). You could also get heavier parts by air freight but it may be cheaper to ship them (4 weeks).
You get them at a fraction of the cost you would buy in Kenya.
Axle [4x2, 6x2 and 6x4 where a 6x4 has three axles, with two of the axles driven]
You are likely to get 6x2 where 3 axles but single axle drive... similar to 2wd car.
You do not need to know about that anyway. What's important is what you want the truck for and GVW (gross vehicle weight) eg 38-44,000kg.
I can send you images or examples to have a clearer view.