i have 489 case open... how/what do i need to make a sure-grip?

Check Randy's Ring and Pinion, Summit Racing, or Jegs for parts. You should just need the Sure-Grip unit and a new ring/pinion set. It is definitely not a "drop in thing". It will need set up for backlash, preload, etc. The factory Mopar manual does a nice job of explaining it. I did mine myself with no prior knowledge; just a Mopar service manual and a press. If you're not up to doing it yourself, you can buy a third member pre-set-up from Randy's Ring and Pinion, but they're pricey.