You may have better luck getting an entire 3rd member w/locker installed from an early Samurai and just drop that in. I believe, but it's before my cup of coffee, that the carrier has a different cross pin configuration on the spider gears and the lunch box locker may not work well with that. It's been awhile and I'm fuzzy on that.
A donor '86 to early '88 is what you should look for. The bulk of Samurai sales were '86 and '87.
Hope that helps, Eric