Check at GMPartsGiant.COM and find out what the parts you're looking for are called.
Steering housing - Would that be the steering column, the steering rack, or something else?
Rear wheel alignment arms - Referring to
http://www.genmotorinfo.com/FullIma...SUSPENSION/REAR+-+MN07-004&pid=020711MN07-004 , are you talking about part 11, or parts 15 and 19?
If 11, it's called a trailing arm, and RockAuto lists the Dormans at
http://www.rockauto.com/catalog/raframecatalog.php?carcode=1055494&parttype=7504 .
If 15 and 19, they're called lateral links, and are listed at
http://www.rockauto.com/catalog/raframecatalog.php?carcode=1055494&parttype=10414 (rear front and rear rear are the front and rear links, on the rear of the car.)
For 15 and 19, a good substitute would be the Grand Prix arms, which almost fit (you would need to make washers for the spindle, since the hole is a bit larger than the Malibu unit was) and which would make the back end stay a bit more "planted" in hard cornering. OTOH, you may not need or want to do that ... which is find, the original GM design, whereas a bit sucky, at least works for what a family flivver would normally be driven as
RwP