Dana 44
The '44 has been offered in scores of applications since its introduction in 1951, so it's easy to find in junkyards. They came in both low-pinion and high-pinion models, and the centersection was even used in '80-and-up Ford Twin-Traction-Beam applications. They were offered in 5-, 6-, or 8-lug bolt patterns.
Applications: Front and rear.
Type: Mainly semi-floating, although there were some very rare full-floating units.
Spline count: 30 (after '72; prior to '72, some were 19-spline).
Factory ratios: 2.76:1 through 5.89:1.
Maximum tire size for stock axle: 35-inch.
Strong point: Wide availability and significant aftermarket support in parts and upgrades.
Weak point: Carrier and spider gears, U-joints, ring-and-pinion.
Junkyard jewel: Find a front axle out of an early '80s Dodge 3/4-ton because they were equipped with locking hubs. Also, a front axle out of a '76-or-earlier ½- or ¾-ton Chevy has steering knuckles that are cast flat and easily adaptable to crossover steering.
Building secrets: Upgrade the stock carrier and spider gears because they're notoriously weak. Also, if you've indexed the axle to improve pinion angle, use a diff cover from a '78 or '79 Ford ¾-ton high-pinion '44 because it allows for a larger quantity of lube and a higher fill point.
Aftermarket alternatives: Currie Enterprises, Custom Differentials, DTS Custom Service, Dynatrac.