I own several CD-x holsters. To make a long story less long, CD-127 is intended for 4-5 inch revolver barrels and semiautomatics, CD-128 is intended for 6-inch revolver barrels. I have confirmed that there is a little wiggle room on barrel lengths. One last thing, holstering is unusual. You do not push or shove vertically into a pouch. Enter the muzzle vertically until you feel resistance, then twist the barrel axially to spread the clamshell while pushing, holstering the gun. The basic configuration is identical. Overall length available for barrel is different.
I believe if you search carefully on this sub-forum, you will find images of old John Bianchi catalog pages including the CD-x series.
If you are unable to find any, email me for them.
Hope this helps.