The shift turrets are different with the Mk2 box having two detent slots on the gearknob ball to the Mk1s one, the wiring connectors for the reversing light switch is different but the switches are inter-changeable and the top right (viewed from below facing forwards) bell-housing casting is a slightly different shape and as such the wiring/pipe clip that lives on that bolt needs to be flattened a bit for it to go onto the Mk2 box.
Otherwise all 5speed ratios are the same, as stated above, get a nice genuine low-milage unit to go in and you can`t go too wrong
Eunos R2 Limited Supercharged 1.8 `White Lightning`also a Eunos J2 Limited 1.8 very low milage.
Ex-`Member of The Glorious Green Gang
Organiser of annual `Nurburgring on a Budget` trip for MX5/Eunos only.
Any work you do to your car is entirely your own responsibility. If in doubt, you should check technical advice with an independent , qualified person who has seen your car. Dr. Eunos of the MX5OC accepts no responsibility for any damage caused to your person or property as a result of you following or not following any advice offered on this forum.