Its a stock box, about 6 months ago when I would pull out in 2nd gear I could hear a rattling sound similar to the sound of a loose muffler(thin metal tapping together) this would only happen at low rpm's. Last week I took a road trip stopped to get fuel when I pulled out of the station, not immediatly after about 2 seconds I could hear the gears grinding in the trans., they would only grind for a second. This would happen in 2nd through 4th not in 5th. I ended the trip made the 100 mile trip home all freeway in 5th. As I was approaching my home shifting through gears, still grinding now in 5th as well. Is it the throwout bearing?

 

Dutchboy, I had similar symptoms, and it was the rear countershaft bearing. The bearing had blown apart & the countershaft was loose. You can check it by taking off the rear tranny housing & look to see if you have play in the countershaft (below the 5th gear shaft).