i have a 1999 s80 t6. i see that we all have the 4t65e transmission. browsing the internet the other day i had come across a 4t65e awd from a 2004 xc90 t6. seeing these two transmissions carry the same id number im thinking this xc90 transmission should fit because both transmissions sit in the same place. furthermore im curious to know if the s80 awd t5 uses the same subframe and rear diff and if it has the same gearing or would i have to get a xc90 rear end and subframe as well . im sure i need the gas tank and all these other little things but in the grand scheme i think it may work. let me know how you feel.
if you wonder why? what good is 300hp to the front wheels? thats my problem. and when i build the transmission im looking for 400 to the wheels. front wheel drive is not on my agenda plan. thank you for your time

 

You're probably just going to have to try it and see. I don't think a lot of people are spending that kind of time and money into an old S80. There's more than just the trans and differential. The DEM is what controls the AWD and it has to communicate in the network. Honestly, it's just not worth it.

 

What is a dem? I am not familiar with the terminology, I'm coming from a mitsubishi eclipse awd background so I am new to my volvo.

 

Ok I see differential module that does look like some wiring and a whole lot of complexity. I would say I need a crashed xc 90 t6 that is not hit too bad

 

It won't worth but if it is for experiment or learning then go ahead and don't forget to share your experience.