This chart should help you identify which current replacement stylus will fit your cartridge.
http://www.gradolabs.com/frameset_main.htm
You might post a picture of it and see if we can help identify it. I'm thinking its likely the G+, which you'll see on the chart.
No, it's not the G+, which I own, and which has (surprise, surprise!!) G+ on the front.

As a matter of fact, all of the models from when I bought it in the 1980's were designated with a "Plus" on them - G2+, G1+, GF1+, etc. Mine's buried deep in a cupboard in a spare room at the moment, so I can't easily get it out and check for you, but I remember that it does have the + on the front. It's also dark brown, not beige.
If you have a look at the Gradolabs picture of their current cartridges, you'll see that they have a G (for Grado?) on the front of all the Prestige series, and anything from a Black to a Gold stylus will fit it, I think, depending on how much you want to spend. The only real differences in the bodies are in the coil wire used - the main differences are the styli, I think, and you can upgrade. As the current models are dark brown. I suspect it may be an earlier model, but Grado don't give much info away, unfortunately.:nono:
However, I can tell you that the styli are interchangeable between certain cartridges. Grado say that my G+, which I bought in the 1980's, uses the Prestige Silver stylus as a near replacement for its original, and it can be upgraded to a Prestige Gold.
You'd probably need to check with them to find out for certain - they may be able to tell you how to distinguish between models for sure.
-Don