Everything have one explanation (I hope)
We are working, at the same time, in several projects:
1-The Universal Carrier (for 4 years).
2-US Comando 4x4 (about 1 year).
3-A 1944 GMC (about 2 years).
Among several others, like a Sherman Grizzly . . .
The GMC axles are very similar to the UC ones
Then, someone change and mixed the location of the GMC and UC axles
So those things can not be mixed ! And do not fitt if changed (Now you know ! ! !)
Now all the parts find their home perfectly
Thanks for all your very kind advice
Joćo