[Tigers] Help with installing 3.07:1 rear gears, please!

[MAURO D'ANGELO]

I am getting ready to install a posi with a 3.07 gear in my Mark 1A Tiger.
I know this might seem like a dumb question to the experts, but I think all
of the new or recent pinions out there now have 26 fine splines and the
original 2.88 pinions had 10 coarse splines.  So when I install the 3.07
gear and pinion, I already know that I won't be able to connect my
driveshaft to the new pinion because the splines won't be able to mate up.

I think this can be resolved by changing the companion flange to one that
bolts onto the driveshaft the same as the original, but bolts to a pinion
with 26 splines.  There are two problems with that:  First, I have no idea
what manufacturer or part number I would need.  Second, I don't know who
would be able to sell it to me and how much it will cost!  Can anyone help
me with this information, please?  Thanks!!!