About Miatas from different years...

[LS20]

miata.net has lots of good info
the most prominent changes were the engine, and i believe there were minor suspension changes in the early 90s

 

[Actaeon]

Here, I forgot to add another comment. I ripped that from a post I made on Miata.net and made a few changes. You can see the original thread here., with some input from others as well .

 

[Shawn]

Oh, almost forgot. In 94 they added the passenger airbag!

 

[adams]

Thanks for the replies and the flaming

 

[Shawn]

Oh, the 94 was also the first year to use R134a for the ACs.