The SJ did come in 2 and 4 door versions. The engine options were the AMC I6 and AMC V8. The top engine was a 401 cubic inch V8 that was well-known for its durability.
The SJs ordered with the bulletproof TH400 automatic transmission by GM got the four wheel drive QuadraTrac system. The system was very advanced for the time and would not allow the rear wheels to spin when the front wheels had too much friction. This vehicle could not go on a standard dyno, because the rear wheels would not receive 100% power ever.
Many of the parts for this vehicle came from a multi-manufacturer parts bin (I bet it was a big one). The brakes, for instance, were straight from General Motors.
These SUVs were more heavy duty than competitors like the Chevy Blazer. They received more durable parts and would run a lot longer. They are also prized by some collectors, if in good condition. Even in poor condition, they can make excellent work vehicles on farms and other industrial sites.
You can sometimes find these listed on eBay for relatively low prices.