I have done many foreign axles, only a couple of domestic.
Yes, there should be an axle (slip yoke type setup) that gois into the trani. Most of them seem to pop out with a slight pry of a kro bar. There is typically an expanding snap ring type retainer that just holds them in until you get the axle into the spindle.
Never done a FWD Buick, so not exactly sure. Hopefully others will help.
Good luck!