Are all '87 GT cv replacement axles the same, if not which is the best pic ?

brand may not matter...

make sure axle length is right.
Put both on a bench and Compress the inner CV.

See my Cave, Axle
While has a list for length. Check them side by side is best.

Even then Do Not give or return the core until the job is done and tested. Many "rebuild" axles have problems right out of the box.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

I doubt there's much difference in quality between the axles available for the Fiero. I picked up a Duralast manual transmission axle at Autozone and it's been fine. Lifetime warranty. Probably 8k miles on it so far. This same axle is on Rockauto as being Suntrack / Trakmotive.

Edit: I did compare the Autozone axle side by side compressed with the original OEM axle. They were the same length.

[This message has been edited by AsaBergman (edited 06-29-2020).]