If I had a paid-off gas-guzzler I'd consider a Diesel swap
In certain cases, a guzzler ends up as the only option for some customers who need a vehicle with an enhanced cross-country ability, since compact (S-10 Blazer, Isuzu Rodeo/Amigo) and subcompact (Chevrolet Tracker) SUVs are nearly extinct back there with the crossover-type SUVs trend. By the way, an uncle of mine consistently got 42MPG with an old Suzuki Vitara he retrofitted a Volkswagen 1.6L early Diesel into.