308 and aussie M21 was always standard with 3.36. 3.55 was performance option and 3.08 was economy option.

In HQ and HJ, 253 and M20 was standard with 3.08, performance option was 3.36 (or possibly 3.55).

HX and HZ 253's were dogs so they made the 3.55 the standard dif with 253 and M15 or M20 to make them feel faster. Economy diff was 3.08 except on tonner where 3.36 ws the economy option. 3.36 was standard with HX-Z 253 if M21 was optioned (passenger only).

Which one you use comes down to tyre size and what you want it for. If it was simply for a weekend cruise car I'd even consider an M22 behind a 253 or 308 with a 2.78:1 diff to give it OK highway capability and still be OK in first. Standard-ish 253 M20 in a ute would be fine with a 3.08, just no good for reversing up driveways.