Kevin, your Green paint strip is also confirmed by the MPC.
I also have 1966 build sheet codes for front springs of
- , [4], [W], [X], and [6].
The [6] was used on an export car with special suspension headed for Sweden - and I cannot pin down an appropriate application just yet. Could be an anomaly.
As I mentioned earlier, the
- was used on 6 cylinder cars, and by referring to the MPC looks like it refers to the Green 1344 lb. springs.
The [4], judging by the applications, looks like it refers to the Gray 1490 lb. springs.
The [W] looks like it refers to the Brown 1491 lb. springs.
And the [X], the Red 1413 lb. springs.
This are preliminary findings - and I could use additional build sheet samples to verify same.