Ratio of final gear 1976 datsun pickup

Maximum speed is determined by engine rpm, divided by transmission gear ratio, divided by final drive ratio, times tire circumference (tire diameter times 3.14) However, the electronic governor limits the 2001 expedition to around 100 mph.

the tires will run best at 28psi for every day running but if you are a hard driver or carry more people in the car then they can be put up to 32psi. To have the stickers in a foreign language suggests that the car is imported outside the normal system and may not comply with your countries vehicle construction standards and you may have difficulty getting spares when required.

The wheels could have been changed on the car from the standard original factory set and hence the tyre size may not be the standard factory original size.
The size of the tyres on the vehicle now is moulded into the side wall of the tyres and is easy to read.
Check all 4 tyres because larger size tyres may have been fitted as a pair to the rear.

The size might read - for example 245 45 18 or 235 45 17 (there are a huge number of sizes for each model of tyre).

The first 3 numbers are the width of the tyres in mm eg 225 mmm or 235 mm and so on. The second 2 numbers are the tyre profile size or ratio (which can be 70 65 60 55 50 45 40 and so on. The third number is the wheel diameter size. If you have 18 inch wheels on the car the tyres will read 18 or if they are 17 inch wheels the tyres will read 17 and so on.

. Axle Code >>>>>>>>>>>Standard
2YN Gear Ratio >>>>2.56<<<<< Ring Gear Diameter 8.5 Standard 2GA Gear Ratio 2.73 Ring Gear Diameter 7.6 Standard 2GB Gear Ratio 2.73 Ring Gear Diameter 7.6 Standard 2GH Gear Ratio 2.73 Ring Gear Diameter 8.5 Standard 2LW Gear Ratio 3.08 Ring Gear Diameter 8.5 Standard 2LR Gear Ratio 3.23 Ring Gear Diameter 8.5 Standard 2LY Gear Ratio 3.23 Ring Gear Diameter 8.5 Standard 2LT Gear Ratio 3.23 Ring Gear Diameter 8.5 Standard 6YF Gear Ratio 3.23 Ring Gear Diameter 8.5


Axle Code>>>>>>>>> Limited Slip
2LQ Gear Ratio >>>>>>>>2.93<<<<<<<<<<< Ring Gear Diameter 8.5 Limited Slip 2YG Gear Ratio 2.93 Ring Gear Diameter 8.5 Limited Slip 2LX Gear Ratio 3.08 Ring Gear Diameter 8.5 Limited Slip 2ND Gear Ratio 3.23 Ring Gear Diameter 8.5 Limited Slip 2LZ Gear Ratio 3.23 Ring Gear Diameter 8.5 Limited Slip 2LS Gear Ratio 3.23 Ring Gear Diameter 8.5

The only way to accomplish that is to change the axle gear ratio. Trucks are generally geared for hauling, towing, plowing, etc, so you have more torque and power at lower speeds. If you change the axle ratio,your low end performance will probably suffer (sluggish acceleration at low speed). Basically, your T100 is not designed for 70mph highway driving.

it is OK as long as the tire will match the original diameter, if the tire is taller or shorter it will cause shift problems if it's automatic and will cause the fuel ratio to be off and will cause it to use more fuel unless you change out the computer chip to match the tires, since tires revolutions are counted by speed sensors it's going to cause you some issues.

High to low /low to high ratio, you will need to be stopped and the transmission in neutral for this to be changed.
The 2wd - Auto - Lock switch can be switched at any time, as it operates an electromagnetic clutch - 2wd is rear wheels driving only - Auto - is to automatically engage 4wd when wheel slippage is detected (this also happens when turning at intersections, due to the inside wheels having a shorter path to the outside wheels, and can give a binding effect on sealed roads (I don't drive with it in auto on sealed roads) auto is excellent if you get, or expect wheel spin from an intersection when wet, just flick it on before or when you have wheel spin, also on gravel roads, having it on auto will greatly reduce the sliding of the back end, and make the car noticeably more stable.
Lock - this locks the differential, which further reduces wheel spin, when in mud / snow, but this will also make the car not want to turn corners, due to it resisting the different distances traveled by the inside and outside wheels.
A/T switch - this actually has 3 positions, and changes the shifting points of the automatic transmission - the middle is normal - Hold is to hold the gear longer, to improve fuel economy, and not change down (kick down) as quickly - Power has the opposite effect, it makes the transmission change down sooner under acceleration.
Also the O/D (overdrive) button on the side of the Tee shift lever, is to engage / disengage overdrive (5th gear) - never do heavy towing in overdrive, this will cook the transmission and overheat the engine (due to the radiator being used as a heat exchanger for the transmission fluid.
Another little quirk - if the transmission light starts flashing every 40 to 50 km, this can indicate that the wheels are different diameters (a flat tyre, or tyres have been swapped around and the spare is more or less worn than the other tyres), the computer will pickup that the wheels are turning at different speeds.
When cold, it is normal for the transmission to stay in 3rd (2-3 minutes of driving), until it has warmed up, and then stay in 4th for a few more km's (5-6 minutes), before it has warmed up enough to change into 5th (overdrive).

the reason it might be shifting so early is because of the gear ratio in the rear end of the truck. it is common in the 2 wheel drive basic model pickup because they were designed to work not travel.

change the pinnion and gear in the differential

where did the tyres wear if it was on the inside, outside, or sides only sounds like you need a wheel alignment.