If you use anything but the 89-95 Mustang MAF, you'll need a custom tune to match the MAF to your computer.
94-95 Mustang GT MAF - $40-$100. It is 70 MM instead of the stock 55 MM on regular stangs built prior to 94. It uses a slip on duct on the side that goes to the throttle body and a 4 bolt flange on the other. You need a flange adapter to fit the stock slip on air ducting that goes to the air box. Wiring plugs right in with no changes. *1 *2
1.) Metal flange adapter
Kurtz Kustomz Motorsports, Inc. KKM Buy the TR70 for $44.95. Or spend some time on eBay looking for one that may fit.
Try AutoZone and ask for 81413 - Spectre / 3 in. Aluminum Intake Mass Air Flow Sensor Adapter at $12.00. You may have to order it online.
*2.) MAF & sensor interchange
The 94-95 Mustang 5.0 MAF & sensor is also found on:
1994-95 Mustang 3.8L F2VF-12B579-A2A,
1992-94 Crown Victoria 4.6L F2VF-12B579-A2A,
1994-95 Mustang, Mustang Cobra 5.0L F2VF-12B579-A2A,
1992-94 Town Car 4.6L F2VF-12B579-A2A,
1992-94 Grand Marquis 4.6L F2VF-12B579-A2A,
Evidently the –A1A, -A2A, AA, etc. on the end of the part number is a minor variant that did not change the operating specs. You should be able to ignore it and have everything work good.