I don't think the gear ratios changed - I do know they changed the bellhousing and front bearing retainer (to convert from the "internal" slave to the "external,") and that sounds about like the right timeframe.
If you see a sleeve around the input shaft, make sure you get a shift fork and pivot ball with the bellhousing, since that sleeve indicates an "external" slave and a (much cheaper!) throwout bearing without an inbuilt slave cylinder.
Meanwhile, I need a bellhousing, shift fork, and front bearing retainer to compleat my own conversion...
Also, know that there were (apparently) two pilot diameters in use with the AX-15, and I have no idea when they changed. However, I do know that, when converting from the damn Peugeot, you commonly end up needing a pilot bearing/bushing from an early 1970's CJ w/304V8 and 3-speed, but I pulled my AX-15 out of a 1990 and it had a much smaller pilot - it was the same size as my Peugeot. Just keep it in mind...
5-90