.The truck does everything better. The fullsize SUV seems obsolete to me.
.What year did the suburbans stop having a solid front axle? I think it was the late 80's early 90's? The OP says he wants a "sturdy axle"...I'm assuming you mean a solid front axle? If that's the case then forget the suburban unless its an older model with a solid front.
The X came with a beefy solid front axle. Plus, any aftermarket mods look better on the X than the do on a modern suburban. To me anyways...
I want to say Excursion or Suburban.
But there's a reason the Excursion is toast. Everyone that had one moved on to a crewcab short bed, or long bed F250/F350 pickup truck. The truck does everything better. The fullsize SUV seems obsolete to me. Unless you're a pet dog. Then you're crated up in the bed, sliding around the bed under a cap (hopefully), stuck at home, or on a spit over a campfire.
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Really? I want to see the pickup that can carry 8 adults in real seats with seat belts and still fit in a suburban garage.
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No Expedition ever came from the factory with a solid front axle. In fact, Ford's half ton trucks and SUVs dropped the SFA in favor of the TTB in 1980.
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Last year for SFA in the Suburban was 1991 I believe, the old "square" body style. The Expedition lost the solid rear axle in 2003 or 2004 I believe, while the Suburban still has it.
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EDITED TO ADD: Just occurred to me that by "x" you may be talking about the Excursion, which does indeed have a SFA, so my bad.
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I just did a quick CL search and was frankly surprised at how cheap the used Excursions are. Saw a couple for around $4000. No idea of condition, of course.