Mazda stock ratio is 4.44:1 on my vehicle. (It's a 4x4. Not sure if the 2wd is different.)

89-93 B2600 Gear Ratios
1st.) 3.730:1
2nd.) 2.158:1
3rd.) 1.396:1
4th.) 1.000:1
5th.) 0.816:1

The 1986-1988 Models with the Mitsubishi engine had 102 HP @ 4000 RPM and 132 Ft/Lbs Tq @ 2000 RPM.

The 1989-1993 Models with the Mazda engine had 121 HP @ 4600 RPM and 149 Ft/Lbs Tq @ 3200 RPM.

Stock tires are 235-75R15's... I'll see what RPM's I'm turning in various gears at various speeds when I drive to work today.





BTW, on the exhaust being opposite, On the B2600i (EFI Mazda engine) It's on the driver's side (left) of the engine.

On your B2600 with the Carbed Mitsubishi engine, it should be on the passenger's side (right) of the engine.

Note the photos here of a 4G63 conquest engine in the B2600 4x4. The exhaust is on the same side as the driveshaft. (Driveshaft drops on the passenger's side.)

Exhaust is no big deal.