What's the difference in the speedo gears in various t-cases? (if any)

I've got a choice of either using a tcase from a '93 auto or a '91 manual.
I'm looking to go to 32" or 33" tires, tranny will be an auto, diffs will be 5.12.

I know the auto tcase and 5.12's with 31's is very close to accurate, but wondering with 32's or 33's if I could source some other speedo gear to help the correction. One of the tcases is getting 4.24 gearing so would be nice to address the speedo at the same time.

I'm assuming here that the trac/kick speedo isn't adjustable like the sami's are (which is really too bad).