Please initially identificate the axle type!
Spicer- Axle: Differential housing is covered by a tin lid.

ENV Axle: The Differential is stuck into the axle housing from the front.

Spicer Type M27: The Drive shaft pipes have an outer diameter of 57mm, M30 has 63,5mm pipes.
The transmission ratio is noted on a flag at the differential lid or noted on a plate at the bottom of the axle at later types.