1998 Gearbox into 1990 SW20

[RomanV]

Hi there.
I have a gearbox from a 1998 MR2, which will be going into a 1990 MR2.
(both NA models)
I have heard that the speed sensor has changed from a mechanical one to an electronic one. Is this true?
If so, will this cause any problems?
Are there any other differences?
Differences that would affect swapping the gear boxes over.
I know that the later gboxes had better synchros etc.

Cheers.