how easy/ can it be done is it to put an V70 radio into a 850?

 

As long as it is a 99 or 2000 radio it should slide right in and work.

 

Thats what I am running. Swapped for a CD player and added a changer to the rear. Works great.

 

this one has an in dash 4 disc changer, and dolby pro logic....

 

It should work but the Pro logic will not work correctly. But should still sound good.

 

well it has the extended plastic piece to the right side of it. Model HU 803, which is apperently for 2001-2004 v70/s60

 

The 01 and up radio's will not fit.

 

If you go to the trouble of swapping for newer you will:
1. Cut wiring, or make a harness adapter female to male adapter, Metra makes the parts
2. Add a new antenna for reception
3. Modify both the dash and radio to make it fit and look nice

After market would be an easier route.