The alpine deck is getting to OLD in the tooth & not reliable any more.
I have the deck from the EF FAIRMONT in the garage sitting there gathering dust.

Can I just pull the alpine out & plug & play the EF deck with the stacker?

No - different plugs in the back of the head unit. Buy a loom from super cheap auto for your factory wiring. Then make a loom which plugs between your EF Fairmont head unit and car wiring and it should work. All wires should mate up 100% ie, speakers, powering up, lights and antenna.

The head unit itself should fit in the same place as the Alpine system.

Put up pics if not sure.