In my 95 B2300 (Ranger with Mazda badges) 2.3L Lima 5speed and 3.45 axle ratio, I can get 25-28 Hyw MPG. Only downside is, OD and A/C are not compatible. Well, not if you want the air to blow out anywhere other than the defroster.....
Gonna be swapping in 4.10's soon. I bet the hyw MPG doesn't drop much, if any.

Long story short, avoid 3.45 rear gear at all costs. Too high for a 4 cyl 5 speed. Sometime around 97-98 they dropped the 3.45 and went to 3.73 gears as the "base" ratio.
Other than that, even the older Ranger's can get decent mileage, so don't overlook a good clean low miles older model. If it's cheap enough, and has the 3.45 axle, that can be rectified fairly easy.