Mazda B-Series was created in 1961.
The Mazda B-series truck
All Mazda B series engines are interchangeable.
The vast majority are manufactured by Mazda. Exceptions are the Mazda B-series pickup, Mazda Tribute, which are made by Ford.
You can learn all about the options on all Mazda vehicles at MazdaUSA.com. For the options on the Mazda B series trucks you can refer to this PDF file (adobe acrobat required) http://www.mazdausa.com/MusaWeb/pdf/specs_features/veh_specs_TRK.pdf.
Any buckets from a Mazda B-series pick up of the same body style. The Mazda B series is a Ford Ranger with different lights, badges, and slightly different quarter panels. But 99% of your Ford and the Mazda are interchangeable. Even the doors, dash, headliner, etc. I have a 94' B series.
2.6L (2555cc)
Ford designed the Ranger. It's rebadged for the Mazda B-series.
Front wheel drive Mazda transmissions used with the B series engines.
Older Kia engines are a permissioned replica of the Mazda B-Series engines. That being said, there is likely to be subtle differences between the two. Installing bigger, faster B-Series Mazda engines into Kia is a much talked about subject.
The front dash speakers in the 89 Mazda b series pickup trucks are 4".
No. Ford Ranger is made by Ford. Mazda makes a "Ranger" by a different name called the B-Series which consists of the B-2300 (2.3 L4), B-3000 (3.0 V6), and the B-4000 (4.0 V6).