The Diablo 6.8 was a limited run by PWS, and they might release it again, but for time being, PWS is not building 6.8 Diablos.
The Diablo 6.8 7" upper is really nice, and it is pricey, so we only sold a handful, compared to the 5.56 models.
The 6.8 Diablo is Awsome (I own one), so we will see what PWS will do in the future, but for now, they have shelved the 6.8 Diablo 7" piston upper.
As for what I am building, most of the 6.8 users I have been speaking to are asking for 11.5", 12.5", 14.5" and 16" piston uppers, , and with our new ATAC Gas Piston Uppers the cost of the 6.8 version is much less than the $2k Diablo 6.8.
Our new ATAC Gas Piston Uppers are based on the Diablo piston system, but re-designed to work in a Carbine platform.
I currently have one version on our website priced at $1450 using a 16" WOA (Shilen) barrel, and I will be releasing another 6.8 model that will be equipped with a Chrome Lined 16" 1:11 twist 4 groove barrel that will be priced at $1399.
I can cut these barrels down for custom lengths of 11.5, 12.5 and 14.5 for an extra $50.00.
Plus, I am going to be building some custom ATAC GPU's in 6.8 with the Side Charging Upper (I am currently machining some to work with the new piston system, and I will post pics when I get them done in approx. 3-4 weeks).
Just food for thought..