The 208 will be the slip yoke. I believe the 205 will be also but not 100% sure. I thought the older 205 were fixed yoke and the 80's or so and up 205's slip version. Swapping the 205 to a fixed yoke is easy stuff though.
The GM 208 cannot be swapped to a fixed yoke. There are rumers that you can use parts off of a Dodge 208 (fixed yoke) to convert a GM version but the cases are different and it does not work.
You can swap in a 241 directly in place of the 208 and you can put a fixed yoke on it.
Are you buying another truck?