2005 through Sep.
Here's some statistics. For copyright issues I'd rather not say my source.
For 2005 through September the Ram, F-Series, Silverado, Sierra, Titan, Tundra, and Ridgeline:
Dodge Ram - 318812 units (-3. 2% from same period 2004)
Ford F-series - 694690 units (-0. 4% from same period 2004)
Combined Chevy + GMC - 757649 units (+9. 3% from same period 2004)
Nissan - 67605 units (+13. 6% from same period 2004)
Toyota - 91086 units (+9. 3% from same period 2004)
Honda - 25787 units (not available in 2004)
I'm sorry I don't have stats to be able to break down by 1500, 2500, 3500, etc.
If you add all that together you get the following market breakdown thus far in 2005:
Dodge - 16. 3%
GM - 38. 7%
Ford - 35. 5%
Nissan - 3. 5%
Toyota - 4. 7%
Honda - 1. 3%
On Edit:
The top 5 selling vehicles in the US in September:
1. F-series
2. Silverado
3. Camry
4. Ram
5. Accord
-Ryan