Three-Quarter-Ton 1/4-Mile Assessment:
Out of the three-quarter-ton trucks, it's GMC's new 6.0-liter Vortec Max V8 / 6-speed heavy duty transmission combination that has the best setup for the level 1/4-mile. The gear ratios perfectly match the engine's torque curve.
What's interesting, though, is Dodge Ram's 5.7-liter HEMI transmission gearing. Both our Ram and Sierra had 3.73:1 final drive ratios, but check out second gear (see transmission ratio chart). It's much higher in the Ram, 1.67:1, than in the Sierra, 2.36:1. There wasn't much of a time difference from 0 to 40-mph between the trucks unloaded, but as soon as the 10,500-pound trailer was hooked up the 0 to 40-mph delta grew to almost a full second. The HEMI fell behind because it lugged against that 1.67 ratio. We think the results would have been much closer if the HEMI had the same, or near-identical, spacing as the Vortec Max's cogs. By the way, Dodge is the only truck of the three that uses the same transmission with their gas engines in 1500, 2500 and 3500.
When we compare the V8 powered GMC Sierra 2500 against the V10 powered Ford F-250, the 4.30 final drive ratio in the Super Duty handicapped the truck unloaded but materially helped it while towing - at least at the start of the run. The GMC and Ford trucks swapped the lead with each other twice, up to around 50-mph, before the GMC's six-speed transmission and its excellent gear spacing once again proved decisive - enabling a V8 to beat a V10.
Towing a trailer tells a different story with transmission gear spacing and final drive ratios - which is the reason final drives are lower in three-quarter-ton and one-tons versus half-tons.
When you buy a heavy duty today, one of the few performance decisions still under your control is determining the final drive ratio - particularly for a gasser. There isn't a dramatic difference in fuel economy between a 3.73 and a 4.10, but towing acceleration and less transmission downshifting are going to make the 4.10 a better choice for a gas truck. If you're purchasing a diesel, it's not going to be as important.