The two major suppliers of heavy-duty drive axles for Class 8 trucks, and how their model numbers map to real weight ratings.
Meritor
Meritor's flagship highway tandem drive axle — the direct competitor to Dana Spicer's D-46-170HP.
GAWR range
40,000–46,000 lb
Configuration
Tandem drive, hypoid gearing
Meritor markets the MT-14X as roughly 50 lb lighter per axle than the equivalent Dana axle — across a tandem set, that's real payload capacity, not a rounding error.
Dana (Spicer)
Dana's heavy-duty tandem drive axle family, sized by rated capacity — D40, D46, and D50 correspond to roughly 40,000, 46,000, and 50,000 lb GAWR respectively.
GAWR range
~40,000–50,000 lb depending on model
Configuration
Tandem drive
The model number pattern (D40, D46, D50) is a quick way to read the rated capacity directly off a spec sheet or axle tag without looking up a separate chart.
GAWR (Gross Axle Weight Rating) is the maximum weight that specific axle is rated to carry safely — it's one of the numbers that determines your truck's overall GVWR, along with the front axle and frame rating. Exceeding it is both a safety issue and a roadside inspection violation.
It depends on what you haul. General dry van freight rarely needs more than a 40,000 lb tandem rating, but if you're regularly running near 80,000 lb gross with dense freight (steel, machinery), a 46,000 lb or higher tandem gives you more margin.
Specs reflect common current factory options and can change by model year or region — always confirm exact figures against the manufacturer's current build sheet before making a purchase or maintenance decision.