i have a gst and the drive cups keep braking(part # gs029)does anyone have any ideas as to why or how to prevent this?

Have you considered running gs010? These are the ultra-beefy nemesis cups *note several other pieces would need to be swapped.
Some ways to prevent this are....
don't slam on the brakes
remove diff lock
run on less high bite surface... no black top

what other parts would i need?

I'm not sure if the GS010 is the part number that you are looking for, that is the part number for the hub and knuckle. I believe GSS10 is the pn for the Nemesis heavy duty drive shaft and diff outdrives. I just swapped in the entire Nemesis diffs into mine which will allow you to get rid of the telescoping front shaft as well. See the post titled "Help me build the ultimate CEN GST 7.7 basher!" in this forum and that should answer all of your questions, hope this helps. [8D]

thanks fastxr ill do that

You can reffer to page 5and6 of the Nemesis manual to see what it will take to conver to this type of a diff set-up
The Nemesis manual is availible for download off of our website.