Don Young will be forever linked to the Cubs collapse in 1969, if you need a rundown of that, you can look it up many places on the web.
He was sent outright to Tacoma by the Cubs before the 1970 season, and mid-season went to Iowa, the AAA team for Oakland. No transaction was listed for this.
After some research, I found this article from The Bryan Times of June 25, 1970.
It mentions Young being sold to Iowa as compensation for the Cubs purchasing Roberto Rodriguez from Tacoma.
This doesn't make a lot of sense on the surface. Rodriguez started the season with Oakland, but supposedly went to the Padres and THEN was bought by the Cubs.
Further study is warranted.
Wrigley Wax blog