The key to ebay is the "hunt". You have to look under every possible description, ie, chevy, sbc, chevrolet, gm, gmc, and every other possible abreviation for the part you are looking for.
Sometimes it actually seams like people are intensionaly trying to hide there stuff
Another good idea is to ask sellers if they have anything else for sale. Many times they will sell you something for cheap outside of ebay, just to avoid the hassle of listing and waiting to get the money.
That`s how I got the R230 w/ 4 halfshafts and the driveshaft for 350.00