Explain the 6 prefix on TE/Amp connector 6-292156-3?

TE AMP conn

What does the 6 prefix call out for TE Connectivity/Amp connector part number 6-292156-3?
How does it compare to 292156-3, 2-292156-3 and 4-292156-3?

The Prefix for for these connectors, are calling out the color of the housing material.
No prefix (292156-3) = Natural Color
2 Prefix (2-292156-3) = Blue Color
4 Prefix (4-292156-3) = Yellow Color
6 Prefix (6-292156-3) = Black Color

Click here for the Datasheet which shows this information.

So these adapters will fit and function the same, but will have a different housing color.