So! It's a long story but I now have a 1998 S70 engine in my car vs. the 1996? 850 engine. There are small differences you need to know about if you're going to go with the S70 (or newer I assume) variety for whatever reason. Remember mine is paired up to a T5 WC from a 1989 Mustang.
The end of the crank is different. You will not be able to use the pilot bearing that the early 850 engines, and alex butchka specifies in one of the threads. I used an oilite bushing I found at Advance Auto Parts, they had it on the shelf. The part # is: Dorman brand, #14647. It's a little long, but I didn't bother cutting it down. NOTE only the the OD is correct! It will press clean into the crank, mine was a .002" press I believe. BUT the ID is too small! You will have to take this to a machine shop and get it reamed out.
I had to cut down my input shaft again. I really thing the adapters may need to be a little thicker. My whole clutch assy seemed to shift into the bellhousing by 1/8-1/4" My Tilton hydraulic slave just barely works, it's on the lowest setting and the bearing just does come off of the 850R PP clutch teeth.
The bosses on the block were the same for mine, but were all tapped vs. the 850 block. One of them was an M8 vs. M6 or something, I cant remember.
Also, a note on coils. Autozone sells a set of 5 coils for a 1999 V70 for $200, and they come with a ****ing lifetime warranty. Don't use junkyard coils. We chased an intermittent misfire for days, messing with all kinds of spark settings. Changed the coils, fixed. My dwell with these coils is set to 2.1 ms. I get about 2.5-3 hours on a tank of fuel (10 gallon tank) on the highway and I don't overheat them.
The coil on cyl #1 does not have a mounting thread like the rest on the <1999 engines. You will have to fix that. I've done this two ways. The first was with a Keen Sert. I tapped the head and ran it in there, punched the tangs down, done. The second engine I didn't have one, so I used a reducing stud that was M8 on one end and M6 on the other I believe.