Shifter arm and knob question
 

would this arm
http://www.americanmuscle.com/roush-...it-handle.html

and this knob
http://www.americanmuscle.com/roush-...nob-white.html
fit on each other?

Says the knob is a 05+ item only so no.

yes but on the link to the knob it says it fits on the Roush Classic Shift Handle and I'm wondering if that's the 94-04 one or some other one. what exactly are the differences in threading?

05+ must have different sized threads on them then 04 and earlier.

The threading is definitely different for the 2005+ shift knobs. That shift knob will not fit that handle as far as I know.