How To Tell What Dana Axle I Have: The Definitive Identification Guide

Identifying your Dana axle requires locating specific factory stampings, reading the Bill of Materials (BOM) number, and counting differential cover bolts to determine ring gear size, spline count, and weight rating. Whether you are rebuilding a vintage Jeep CJ, upgrading a Ford Super Duty, or sourcing replacement parts for a classic muscle car, accurate identification ensures you order the correct carrier bearings, ring and pinion sets, and axle shafts the first time.

Pre-Procedure Planning & Identification Checklist

Determining your axle model accurately demands patience, cleaning supplies, and an understanding of Dana/Spicer nomenclature. Over decades of production across automotive, agricultural, and heavy-duty industrial applications, Dana Spicer has utilized several identification methods, including cover bolt patterns, axle tube stampings, and casting part numbers.

• Essential Gear & Tools: Wire brush, brake cleaner or solvent, shop rags, flashlight or mechanic work light, chalk or a grease pencil, scraper, and a digital camera or smartphone for capturing hard-to-read stampings.
• Mandatory Prerequisite Knowledge: Understand that casting numbers on the differential housing pumpkin indicate the part family rather than the exact model, while the stamped Bill of Materials (BOM) number provides the precise engineering build specification.
• Estimated Budget & Duration: Budget between zero and ten dollars for cleaning supplies; the physical inspection and decoding process takes approximately 15 to 30 minutes.

Step-by-Step Dana Axle Identification Workflow

Step 1: Clean and Inspect the Axle Housing Exterior

Before attempting to read any numbers, you must remove decades of grease, undercoating, mud, and surface rust from the axle housing. Crawl underneath the vehicle with a wire brush and a can of heavy-duty solvent to clean the differential housing cover, the axle tubes, and the center section casing.

Warning: Never use a torch or open flame to burn off undercoating or grease near a differential housing, as extreme heat can warp housing tubes or ruin internal axle seals.

Step 2: Count the Differential Cover Bolts and Examine Cover Shape

The quickest way to narrow down your Dana axle family is to inspect the differential cover. Look closely at the shape of the stamped steel cover and count every single retaining bolt securing it to the center section.

1. Locate the lowest point of the differential housing where the stamped steel cover meets the cast iron or aluminum center section.
2. Mark your starting point with a piece of chalk and count the cover bolts in a clockwise or counterclockwise direction.
3. Note the geometric profile of the cover; some Dana covers are nearly symmetrical octagonal shapes, while others feature distinct flat edges, drain plugs, or inspection ports.
4. Cross-reference your bolt count against standard Dana families, noting that light-duty units typically feature 10 bolts, while heavy-duty variants feature 10, 12, or 10 asymmetric bolts depending on the specific application.

Step 3: Locate and Read the Bill of Materials (BOM) Stamp

The Bill of Materials (BOM) number is the holy grail of axle identification. This unique numeric code is stamped directly into the metal axle tube, usually on the passenger side facing forward, though it can occasionally be found on the driver side or on a metal tag bolted to the housing cover.

1. Inspect the top and front-facing surfaces of the axle tubes extending outward from the center pumpkin.
2. Wipe the metal clean down to bare steel, as factory stampings are often shallow and easily obscured by paint and rust.
3. Look for a string of numbers typically starting with the digit 6 (for older Dana axles) or numbers containing a dash followed by a dash and a digit (e.g., 60XXXX-X or similar 6-digit sequences).
4. Transcribe these numbers carefully, noting any suffix letters at the end of the sequence, as these designate specific gear ratios, locking differential options, and brake configurations.

Step 4: Examine the Differential Housing Casting Numbers

If the tube stamping is completely rusted away or rendered illegible by pitting, you must rely on the raised casting numbers located directly on the main differential pumpkin housing.

1. Locate the raised numbers and letters cast into the surface of the center pumpkin, usually positioned near the neck where the pinion yoke enters or on the webbing.
2. Common casting numbers include digits like 44, 60, 30, or 35, which correspond directly to the Dana model family designation.
3. Keep in mind that casting numbers only reveal the general housing family (such as a Dana 44 center section), while the internal axle shaft spline count, gross axle weight rating (GAWR), and ring gear carrier break depend entirely on the specific application determined via the BOM.

Dana Axle Specification Matrix

Common Identification Pitfalls & Field Fixes

• Root Cause: The BOM stamping on the axle tube is completely obliterated by rust pitting or deep gouges from a jackstand.
  
  
  • Actionable Fix: Measure the outer diameter of the axle tube, count the cover bolts, and check the ring gear diameter by pulling the differential cover to match internal measurements against Spicer service manuals.
• Root Cause: A previous owner swapped axles, meaning the vehicle's original factory VIN or door sticker specs no longer match the physical hardware installed underneath.
  
  
  • Actionable Fix: Disregard factory literature completely and rely exclusively on the physical BOM stamped into the axle tube of the currently installed unit.
• Root Cause: The differential cover has been replaced aftermarket with a heavy-duty fabricated girdle cover that obscures or alters visual identification cues.
  
  
  • Actionable Fix: Rely on the axle tube BOM stamping or measure the ring gear diameter and pinion shaft diameter directly once the cover is removed for fluid service.
• Root Cause: The stamped numbers on the tube are faint and ambiguous, leading to misread digits like confusing an 8 for a 3 or a 0 for a 6.
  
  
  • Actionable Fix: Apply a light layer of dark spray paint or chalk over the stamped area and wipe it across the surface so the pigment highlights the recessed stamped depressions.

Frequently Asked Questions

Where is the Dana axle tag located?

Older Dana axles featured a small metal metal tag bolted under one or two of the differential cover bolts. Newer axles rely on a numeric sequence stamped directly into the passenger-side axle tube facing forward. If both the tag and tube stampings are missing, you must decode the axle using internal component measurements and cover geometry.

How do I know if my Dana 44 is a high-pinion or low-pinion version?

A high-pinion axle (often called a reverse-cut Dana 44) features the driveshaft entering the differential housing significantly higher than the centerline of the axle tubes. Low-pinion axles position the pinion yoke directly on or slightly below the horizontal centerline of the axle tubes. High-pinion variants are commonly found in the front of four-wheel-drive trucks and jeeps to improve driveshaft angles.

What is a Dana carrier break and why does it matter?

A carrier break refers to the physical design threshold where differential carriers change size to accommodate thicker or thinner ring gears for specific gear ratios. For example, on a Dana 44, numerical ratios of 3.73 and numerically lower use one carrier, while ratios of 3.92 and numerically higher require a different carrier or a thick ring gear spacer. Knowing your exact model ensures you order a compatible locker or limited-slip differential.

Can I determine my gear ratio without taking the differential cover off?

Yes, you can jack up one rear tire, mark the driveshaft and the tire with chalk, and rotate the tire exactly two full revolutions while counting the number of complete rotations the driveshaft makes. The resulting number of driveshaft turns (such as approximately 3.73 turns) reveals your approximate ring and pinion gear ratio. For absolute precision, remove the cover and divide the ring gear tooth count by the pinion gear tooth count.

Are Dana 44 and Dana 60 axle shafts interchangeable?

No, Dana 30, 35, 44, and 60 axle shafts possess completely different spline counts, shaft diameters, and bearing journal dimensions. A Dana 44 typically features 19, 30, or 33 spline shafts depending on the year and application, while heavy-duty Dana 60 axles utilize robust 30, 35, or even 40 spline axle shafts designed to withstand extreme torque loads.