quick 6v vs 9v zener mod question

Never mind, MTN had info I wanted on the parts listing.
From the FET driver DIY parts listing…

Got a couple zener modded fet drivers (1ea. 20+17mm) laying here, and a triple in a 2/3 cell light with a crap blinky driver.
I know when I ordered these drivers they where for 6V mtg2/xhp50/70 ect. Both are running the older Guppydrv, I am pretty sure had no lvp.

My question is,
Is there a difference in the zener for 6v vs 9v?

Thinking if the driver will handle it running 3 unused xpl-hi’s I have in series with the 3 cell battery tube. Not ideal, but it should work if it dont burn the driver right?

Thanks,
Jim