In my constant search for information on the Getrag 284 and adapting it to Fiero 3.4 DOHC installations, I found some interesting information, shown below, about the Maserati powered Chrysler TC.
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The 16v transaxle is a (TC specific) Getrag 284 with a 2.64 final drive ratio (ratios). This transmission was originally developed for the proposed mid-engine Corvette, but obviously never used, so Chrysler paid for tooling changes to convert the bell housing pattern to their 2.2 engines. The 284 is physically larger than even the A568 used with the Dodge Turbo III 16v and is much stronger. The input shaft is almost twice the diameter of the A568 and the surface area of the TC-specific clutch is larger. The larger size of the 284 differential also translates into more strength.
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HISTORICAL NOTE: The last TC to roll off the assembly line was the famous Arctic White/Bordeaux 16V. Titled as a '90 model, this car was also the last16V. Supposedly built at the request of Chrysler's Robert Lutz, it was eventually offered for sale and purchased by a Chrysler employee in Michigan. It had a build date of April 10, 1990 and a chassis number of 8543, making it the final TC to be built. Loaded with luxury appointments, the TC at 3,000+ pounds was a good bit heavier than it's 93 inch wheelbase would suggest. The Turbo II, detuned to 160 hp, was only offered in '89. Mated with the 3 speed A413 automatic, it yielded leisurely eleven second 0-60 times (go to the PERFORMANCE section for some help with this problem). The '89-'90 200 hp sixteen valve engine with the Getrag 5-speed fared much better, with sub-7 second 0-60 times (R/T 6/88).

We can assume the 284s use behind the 3.4 DOHC means it is stronger than the 282 but how much? I understand that it has to be returned to the factory for a repair according to an owner who went through the process costing "$4700" I wonder why that is, and if it's that much stronger why did it need to be repaired. It might not be worth the trouble to actually seek out with the purpose to install in a non application vehicle unless there is some substantial gain to be had over the more abundant 282.

The 284 Getrag has a torque handling ability of 50 lb.-ft greater than the 282. The German designs are, typically, "Over-engineered," so the published specs on both units are, probably, half the value that they're capable of handling.
Look at all the V8's out there using 282's. Both of these units are strong transaxles. The weak point seems to be the synchros.
All of that said, I'd, still, prefer the 284. I have two 284's, one 282 (Needs synchos replace) & one Muncie 4-speed. I tore up my original Muncie 4-speed (Broke a shifting fork.)
It's true that the 284 must be serviced by GM and it is expensive (Around $3K.) Apparently, they require a humongous press to tear down/rebuild. Since I have two low milage units, I'm not too worried about it. Also, I've never seen a broken 284. I'm sure they exist, but I've never heard of one.