gearbox ratios

[tickle]

i have a spare gearbox from a 1.6 m40 will that fit a 1.8 M10?

i need ratios for these boxes so does anyone know a source i can get these from?

The codes are:-

M40 - 240 0 0366 91
225
32
2

M10 - 240 0 0366 90
225
22
1

[tickle]

i also have a 3,91 open diff + 4.21 open diff, which should i fit to suite the different gear ratios?