Dan -
I know people who swear by the filter thing. To me, it's a mileage issue. Let's suppose you had a filter that caught 98% of the crap in the fuel. That's 2% crap you're feeding the engine. And it's worse crap than you'd ever find in European or American fuel. It might not matter if you're only in country for 1,000 or 5,000 miles seeing elephants or photographing gorillas or driving from Mombasa up into the Rift. But if you plan to spend 20,000 or 30,000 or 50,000 miles of the vehicle's life on the Continent, you're talking about a lot of crap diesel being fed through the vehicle's system. Filter or not, your engine is going to drink some of it.
Generally, for diesels, I would say you're better off with an engine designed to drink crappy diesel (the 3.0TD comes to mind) than a very advanced engine struggling to stay alive while drinking crappy diesel, even if it's downstream of a filter. I often joke to people that you see this on the drive from Kenya to Uganda to DRC. In Kenya and Uganda, you see a fair number of more advanced diesels - late-model Range Rovers, D4D Hiluxes, etc. But as you near the Albertine Nile crossing (a ferry I've taken a dozen times) and continue west, you start to see more and more old TX's and early 70 Series. There's a reason. It isn't that people are poorer or buying older cars - the 70 Series costs just as much to maintain as a Hilux, maybe more if you maintain it to a high standard. It's that the 70 is simply better-equipped for worse fuel and worse roads.
I can put up with the road, fuel, and supply chain challenges of where we live. But I wouldn't live farther into the Continent than we do without a lot more support.
Gauge what's realistic, talk to people who've done it, and figure out your African plan. If you need anything re east Africa, let me know... I'll do my best to help. Hell, I might even tag along as vehicle #2 for part of your trip.
