need 1995 Sonoma help

the problem is that when I put it in fifth gear it slips out within 10-20 seconds. And going up-hill it doesn't even catch. I got suggestions like clutch, trans fluid, and sychcros.... does anyone else have suggestions? thank you

Welcome to the forum.
First is check the linkage adjustment and the washers.

9 times out of 10 it's the sychcros....

Welcome to AF.
We need a good description of what it is doing.
Does it go into 5 th gear and then jump out of gear or just not go into gear?
Can you feel it snap into 5 gear good?
Can you feel it push itself out of 5 th gear.
Or can you hold it in gear and keep it going or pulling?
Or does the engine just rev up on a pull or going uphill?
On a hard pull does the engine rev up in 4 th gear?
Is all other gears good?

Actually, you gotta be going at a very steady pace in 4th gear before getting into 5th. I got a hang of it and it stays in. But theres times where if you give too much in 4th and try to shift to 5th it goes in, then within seconds just slips out. Sometimes you can go back into 5th then its fine but i'm just worried about just giving it too much and end up ruining the whole thing. But all the other gears work well. And uphill the 5th gear slips out and the engine just revs. Thanks all.

Can you feel it lock in gear or snap in good.
Could be shifting stick or a problem inside.
Some shifting sticks have a plastic button the end that breaks out and will not let it go in good or snap in good.