The only tricky part is getting the pinion flange off. Torque spec is 450 ft lbs. Yes 450 - not a typo.
Mark the nut's relationship to the pinion shaft. Use a big impact. You need a puller to remove the flange. Change the seal. When you reinstall the pinion flange nut, turn it just a touch past where it was. This is how I did mine. My friend whose shop I was able to borrow part of (A drive on lift) just shakes his head at me and says "Glad my customers don't have stuff this big".
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'94 3500 4x4, 211,000 miles, Never had a cat, Auto w/shift kit (thanks Dave G), 3. 54 Gears, TST #5 plate, 235-85-16s, Rancho 9000s w/remote, Isspro Gauges & Amsoil Air, Oil & Bypass Filters & Lubes, AWOL intake boot.
Punchlist: 14 cm Turbo Housing, Torque Converter & 215 Injectors.
NRA member.
Blue Ribbon Coalition member.
"I am my own performance station"