That's crazy. I changed the trans fluid and diff oil two years ago in my Firebird. For the diff I got Valvoline Durablend 80W90 from Advance Auto for about $11. I bought the additive from the dealer, but I think it was only about $12. I guess it's gone up since then.
I don't know why dealers jack up the prices to such stupid levels, you'd think they'd figure out they could sell a lot more parts if their prices were competetive. Then again maybe they don't want to sell a lot of parts. For example... the driver's side window motor finally died on my firebird last year, dealer price was around $160. Bought the same identical brand new OEM part at my favorite 'old-style' parts store for $68. I can understand they need to make a profit and they mark up their parts, but that's over 200%.
