How do you replace a positive battery cable on a 2000 Chevy blazer and where can you obtain the cable other than the dealer?

You Will Need To Get The Cable From A Dealer. If The Cable Is Burned Into Ect. It Will Need To Be Replaced. If The Cable End Is Bad You Can Try This. Purchase a New Cable End. Yours Probably Has Two Smaller Cables In The Wire Also Besides The Regular One. On The Cable End You Get Also Get One Or Two ( as needed ) Heavy Duty Cable Eyletts That Fit The Bolts That Tighten The Large Cable To The Terminal End. Put The Small Cables On each Side Of The Bolts That Clamp This Down, Tighten It All Down. Should Work OK. I Have Done This Often. If You Do It This Way. You Will Need To Check These Connections Every 3 Months Or So To Be Sure They Are OK.