The rear axles can become worn over time from low differential fluid or a mechanical failure. Axle bearings can damage the axles without proper lubrication. If you have a leaking differential seal, fluid will drain out, resulting in improper lubrication. LMR.com has rear-end service kits, including proper fluid, friction modifier, and a replacement gasket to keep your rear end sealed to protect your axles! If your axles are damaged in your 1st Gen Ford Lightning, pick up a new set and get back on the road!