G20 manual tranny having trouble shifting into 5th. shifting1-4 are no problem but when shifting into 5th it takes multiple tries to get it into gear.

any idea what this issue may be? i'm thinking clutch but its not my vehicle, posting this for a friend to see if i can help.

 

yeah, it is probably clutch related.. I'm thinking more along the lines of the master cylinder, slave, and/or fluid.
If it isn't slipping badly, then the clutch itself is probably fine, but if the master, or the slave has gone bad, then it won't fully disengage which can make it difficult to get into gear. Same thing if the fluid is old/bad/low. if air has gotten in it, or if the fluid is bad, or has water in it from being old, it will compress into itself, instead of transferring the pressure the way it is supposed to.
I would start there.
I would also suggest a gear lube change. Sometimes that makes all of the difference in the world.
From there, you'll gonna have to tear it apart to figure out what is wrong.

 

How is it going in reverse? Possible shift cable/linkage damage. Or even something rubbing the shift lever when it moves to position 5.