Apparently there are some differences, I picked up a replacement speedo from a Tbird for my TBS and had to modify the plastic 'cup' to get it to work. If you can get one with the cup included you should be good.
Ideally you can make any t3 and some t5 instruments work. As mentioned above some cup modifications may be needed. 95-97 had slightly longer metal gauge cups. Post 97 had shorter plastic cups. Which affected the stud length of the gauges.The later Daytona's and S3's had even shorter retaining studs.
Studs can be changed out from gauge to gauge using a little heat and some pliers. If you switching from T5 S3 gauges you'll need to make new pilot holes where the studs are to go. If you don't have the proper length stud 5mm allen bolts are close to the original stud base size a little epoxy and your back in business.
If you changing out a tach there are couple different wiring connections to deal with.
screw and eyelets
bullet connector
plastic hardshell connector to the back of the gauge
Just make a jumper to match the vehicle harness
Linear Mode
