Why a solid axle?
Unless you're building a prerunner, the factory 1/2 ton Twin-Traction Beam (TTB)
suspension doesn't have a lot of benefits. In fact, once lifted and equipped with
large tires, a frequently-wheeled truck will slowly start to destroy the TTB. Bent
suspension arms, bent drop brackets, and bent and broken radius arms are not uncommon
A TTB truck with a front locker and 35" tires can make a regular habit
of breaking u-joints and axle shafts. Also, due to the smaller 1/2 ton components,
small parts like ball joints, wheel bearings, and brakes will need more frequent
Flex vs. Travel
Another advantage of a solid axle swap is flex. An IFS truck has suspension travel. The
pressure (and traction) available at one tire is proportionate to the amount the spring
is compressed. As the tire droops, less and less traction is available at that corner.
A solid axle suspension works much like a lever arm. As one side of the truck compresses,
forces will tranfer to the droop side of the truck, adding traction to the opposite side
of the vehicle.
Straight Dana 44 vs Dana 60
A Dana 60 Swap is an expensive undertaking. Useable D60 axles typically sell for
$1100-$1200. Add to that the cost of gears, a locker, bearings, brakes, and a king pin
rebuild, and the final cost can approach $3000. This is all before considering the
costs of the suspension components necessary to install the axle.
Additionally, the D60 is an 8-lug axle with dual piston calipers. This typically calls
for new wheels and tires. Custom 8-lug 15" wheels with 2.5" backspacing can fit over the
larger calipers, but many opt instead for a 16" wheel with 3.5" to 4" of backspacing.
Of course, the factory 1/2 ton 5-lug rear axle will also have to be swapped for a rear D60,
Chevy 14-bolt, Ford 10.25, or similar 8 on 6.5" lug pattern axle.
For these reasons, some wheelers opt instead for the lighter D44 solid axle. Ford used a
reverse-cut, open knuckle D44 axle for much of the late-70s. These axles are lighter and
have greater ground clearance than their D60 counterparts. Gears, lockers, and small parts
such as brake hardware and bearings are also cheaper.
Unfortunately, the straight D44 retains weak axles similar to those on the TTB Bronco.
Aftermarket alloy axle shafts are much stronger than stock parts, and high-strength u-joints
like those from CTM Racing eliminate another weak point. The combination of the alloy shafts
and CTM joints will make for a very strong axle, although the strength probably still falls
short of a D60. Expect to pay around $300 for a set of alloy axles, and $150/ea for CTM
The D44 also uses the same ball joints as the TTB trucks. The ball joints don't stand up
well to large tires, especially those on wide wheels or on wheels with little backspacing.
Expect to replace ball joints roughly once a year at a cost of $100 for a set of four.