MR2 2000 Spyder sequential manual 5 speed. Have a leak in Gear Shift Actuator Assembly GSA . It is between the clutch cable and the clutch release cylinder. Can I replace the seal? Research told me I have the replace the whole GSA unit!! Help needed asap thanks

Ahhh, so you have a slave cylinder leak.
 
Probably not the answer you're after but here:

The seals inside the unit are specially made to deal with the higher pressures placed on them from the pump unit.  They are not a conventional viton seal and are a very specific size.  There was a crowd over in Germany who made the seals up years ago, but your chances of finding one are slim-to-none.
 
Your best bet would be to grab a replacement GSA second hand and fit that, to fix your problem.
 
Whereabouts are you located?

Thanks I am in qld.