I have a Pioneer CF-134 shift fork I bought for a spare. I have not installed it but I compared it to the factory fork in a spare Getrag 5 speed and it looks the same.
Maybe somebody has installed one and can verify that it will work.
The lower shaft diameter is the same, the upper shaft on the CF-134 is about .015 smaller than the factory fork. I would use it if I needed to and wouldn't worry about the .015 difference.
I found a review on Amazon of the CF-134 part " Verified Purchase Installed in my 1987 Fiero 5-speed getrag. Fits perfectly."
https://www.amazon.com/Pion...h-Fork/dp/B0049JFMX8RockAuto also says it fits 87-88 Fiero.
[This message has been edited by Larryinkc (edited 11-12-2018).]