The 4D55 was available in rare numbers from the factory in the 1986 Ford Rangers. And yeah, it may need regeared. Most Mazda B2600's and Ram 50's with the 2.6 ran 3.90's with the 5-Speed (904 Automatic Ram 50's were equipped with 3.55's and A500 Automatic Ram 50's were equipped with 4.22's) I'm running 3.73's in my 4D56 D50 with 33" Tires and occasionally 40" Tires. Prior to the Turbo Failure the 3.73s were ok, it may have needed a tad more gear (4.10's) to be a good midway point for both tires.It's a beaut! That motor should fit a Ford Ranger, right? I'd look into whether or not you need to change the gearing too.
in these earlier rangers it would be plug n' play but it's also a good engine for the current ones... i have already seen one of those '93-'97 in an used cars dealer some months ago that had the gasser 2.3L replaced by a 4d56 and no regearing required...The 4D55 was available in rare numbers from the factory in the 1986 Ford Rangers.