Anyone know why?

 

Not sure I understand your question, but if you are asking can you make your automatic car a manual... Yes.

Need:

Pedal Assembly
Shifter Assembly
Flywheel
Master Clutch cylinder
5 speed trans with bell housing
manual trans oil cooler lines

I just happen to have all of that for sale...(except the trans oil cooler lines)

 

Why can't the 4spd auto be a 5spd auto?

 

It is if you count the overdrive and the lock up feature.
Sorry curious question??
T/V

 

Because they didn't make it that way.

 

The auto in a D1 has no electronics. You could stick whatever non-electronically controlled auto behind it that you can make fit, and the computers won't care.

The D1 came out in 1990, and a four speed auto was pretty normal for the time. If there were 4 speed autos, they were likely only on very high end cars, not cars that were basically designed on top of a 1970 Range Rover Classic.

 

So the tech wasn't around, thats why its only 4? So the 5spd man is 12345 and r or 1234 and r?

 

5 speed means 1,2,3,4,5,R

4 speed autos were normal for a long time. They work fine.

 

So the 5spd gets better mpg right?

 

Usually, due to less rotating mass and a direction connection to the engine as opposed to the fluid coupling the auto uses.

But in a disco, I'll bet it's not much better. Maybe 1 or 2 mpg.