40A 208V 2P Range with 6-6-6-6 AL?

[Lbartowski]

I can't find MC cable with #8 AL. #6 AL seems to be as small as the manufacturers go with AL wire in MC Cable.

Any issues with landing a #6 AL wire on a 40 amp breaker or receptacle? #6 Aluminum seems cheaper than #8 copper?

 

[augie47]

no Code issue