Axles,
2004 had a two piece axle, one piece fit into the diff and was held in with a "C" clip. the other 1/2 went to the wheel hub.,, to remove that axle stub you need to remove the rear cover, remove the C clip, if you want to use the ONE piece axel you need to change the axle seal and now just push the axle into the diff. the diff is the same on all crossfires (just not the gears and the yoke) the axles are the same left to right, (they interchange).
Yokes
that is the three leg yoke one on your transmission and one on the diff where you mount the driveshaft . the base and limited uses a smaller yokes, and only the srt uses the larger yoke, to swap them out you also need to change the seals as they are different also
Driveshaft
even though both(limited & srt) driveshaft are the same length the yoke size are different the srt uses a larger yoke. the srt form center bolt hole to bolt hole is 3 3/4" where as the limited is 3 1/2"
Wave-trac
the wave-trac fits both limited & srt, the slk320 & slk32. with the wavetrac you must use the one piece axle

if i left out anything post it or pm me and i will add it. jim