Rear spoilers
If they hold the same as Mustang rear spoilers, YES, the shape and overall width of the spoiler wing the same but the distance between pedestals is different. Since the distance between pedestals is different, the spoilers themselves are also that much different. I know this for a fact since my wife's 70 Mach and my friend's 69 Boss 429 have the same spoiler, but my friend's brother's 71 Mach 1 has a different unit. So yes, the 69/70 Mustang spoiler is different than a 71-73 Mustang spoiler.
Don't think you can just bolt on the incorrect year rear wing. It won't fit!! Since the pedestal width is different, the locating holes will be in the wrong place to use the correct inside (underside decklid) reinforcements. The spoiler brackets use one of the trunk hinge to decklid bolts as well as the through studs to the spoiler pedestals. Since the decklids have different underside profiles due to the different size openings, the locating holes will be too far out of alignment to be held properly by the reinforcing bracket.
Your best bet is to measure an original Eliminator with a wing and see if it is the same as a Mustang unit. Since Mustang vendors have repros available, you might luck out.
Good luck
Cougrrcj