Reply to "Popping out of 3rd gear"

All the possible reasons listed to date are correct. But the most likely is misadjusted shift linkage, or a loose or badly adjusted trunnion support. As mentioned, ANYTHING that prevents a full-length move of the shift shaft into or out of the rear mounted shift box will not-quite-fully engage the synchro slider for that gear inside the tranny. Then under high torque, the syncho slider will move backward into neutral.

I've also seen minor wear and/or linkage misadjustment that prevented full gear engagement unless the AFTERMARKET shift gate being used was trimmed to fit a particular Pantera.