my 73 sb 4 speed standard wont go forward in any gear does anyone know what might be the problem?

you have probably lost third gear gonna need to rebuild trans might have lost the shift forks that slide the gears into mesh

I was able to go for a drive still wount go into 3rd though. Im new to SB maintance thing. Would you recommend looking at the Slide Gears first? If so so how do I go about it?

Check shift bushing, and shift coupler first. My be is the bushing is bad.

check if the clutch is the problem.There should be a clutch fluid reservoir that needs to be full.Joseph.

Uh....no. The older bugs had cable operated clutches. Hydraulic clutches weren't used until vw screwed up and started adding water to the engines!

You might want to look at your shift plate. Located under the shifter. Just put a new onevon. They're not expensive and I replaced mine myself. I'm a girl