Thanks for the responses.
I ended up doing a lot more research and it appears that the shims go between the bearings and the spacer, however it doesn't matter which side of the spacer.
I had to use different shims to get the end play where I wanted it. Luckily the NP205 I was robbing the input shaft from had the correct sizes, so I was able to finish the project without waiting for more parts.
For those who are interested, here some links to the sites that were extremely helpful as I tackled this project.
https://youtu.be/y_npR9NxgR8
http://www.wideopen4x4.com/NP205RebuildGuide.html
http://67-72chevytrucks.com/vboard/s...d.php?t=469726