I believe this might be the one you are thinking of? :) Scubapro MK11 with balanced S600 or S500 or G250I considered this (?) and did a post on it a few years back. I'll see if I can find it.
Looks like 6 or 9 parts + the MK17 service kit. (6 if you get the older version chamber parts that use the same spring, washer, and adjustment screw, 9 with the newer versions)
Anybody know if the MK17EVO dry chamber fits on the older MK17s? (I believe on the EVOs, both diaphragm retainers can be R&R with an adjustable wrench in a pinch for emergency travel service)