I just swapt a 1979 280sx 5 spd in my 1971 240z and it is hard to shift. Its a good tranny it just is hard to shift. What do i do to get it to shift smooth?

I have always found that Redline MT90 will make Z trannies shift like butter. You might try that before looking for anything wrong inside.

Second the MT90 - it helped mine shift smoother.