In general most screws and bolts are made from steel or stainless. When tapping aluminum and inserting a steel/stainless screw the effects of galling can have an adverse effect. Anodizing can help but in general tapping aluminum for a standard screw is a no no. Use a similiar metal for mating threads. Use helicoils or Pem F series flush nuts or CLS series pem nuts if space is an issue. In terms of manufacturing cost it is much cheaper to insert threaded inserts that to manually tap multiple holes
If you guys are still looking try these
http://www.greenlee.com/archive/MA-4426.pdf
or BOSCH 1462 VS 3/8" TAPPER