It isn't that simple. You would have to disassemble the entire trans to replace the tail shaft and housing.

If you check www.car-part.com you can easily find a 727.

 

will the 727 bolt up to the 318 and the np208 or will i need mods?

 

Yes a 1978 or newer small block 727 will bolt up to both the 318 and 208

 

will any drive shaft modifications be needed or is the length close to the same on a np435 and a 727? and can it also bolt to a 360 because in the future i want to swap the 318 for a 360

 

Yes it will bolt to a 360 as well but keep in mind that the 360 torque converter will have a balance weight since they are externally balanced whereas the 318 is internally balanced.

I don't know what the drive shaft differences would be specifically. But just be prepared that they maybe as well as a different cross member.

 

So snce I have a 1991 with a 4 speed and would love to go auto....4sp auto, can I get an auto that came in a truck or ramcharger and will it swap directly in since My truck is a 91? In short, were the 1990~93 Dodges available with a 4sp trans?

 

90-93 would have had the A518 OD transmission.

In your case you would also need a computer from an auto trans truck to work with your fuel injection and shift it in and out of OD.

I would be willing to bet if you advertised wanting to swap your manual trans for an automatic set up someone is bound to want to switch.

 

I think you are probably right since everyone cept me seems to want a manual! I'd love to do a straight up swap for the man to auto. Were the A518 a reliable trans with the 318 in front of it?>

 

The A518 was a 727 with an overdrive. It is a very good transmission.

 

That is great to hear! I do know the 727 was one of the wolds great autos!