I'm chasing a 1st gear out of a 094 syncro box
3.77777:1 ratio which is different to all the 2wd boxes

Anyone got one?

Try Weddle in the USA.
The 3.778 1st gear from the Synchro is the same part number as the 4 speed 094 that is quite common over there.
091 311 251A
Replace the operating sleeve as well.(091 311 255A)
They have very little engagement, so the slightest wear and they will pop out.

(normal 2lt 091 1st gear is 091 311 251 and does not fit) It's part number has no suffix 'A')