Following for N/A 3800s to help clear any confusion:
97-03 GPs have 3.29 Final Drive (3.29 diff, 35/35 gears)
04-08 GPs have 3.05 FD(3.05 diff, 35/35 gears)
00-05 Impalas have 3.05 FD (3.05 diff, 35/35 gears)
00-05 Monte Carlos have 3.29 FD (3.29 diff, 35/35 gears)
Other:
00-05 Impala/Monte 3400s have 2.86 FD (2.86 diff, 35/35 gears)
06+ Impala/Monte 3500s have 2.86 FD (2.86 diff, 35/35 gears)
06+ Impala/Monte 3900s have 3.29 FD (3.29, 35/35 gears)
3.29s hit 6000rpm in 1st gear around 45mph, 3.05s do it around 50mph, 2.86s around 55mph.