i have a 88 turbo2 s4 rx7 and im swapping a s5 motor into it i tried putting the drive shaft in but it turns out its to long, its a s4 drive shaft. i need to know if swaping the s4 motor with a s5 do i need to get a s5 drive shaft or am i going to have to custom cut this drive shaft????

 

You have a problem, there is no difference between the S4 ad S5 driveshaft.