What model jake heads are these?

I bought complete used set of 346D from Midwest Diesel last year. Very fairly priced. They also had brand new 346D surplus kits. Cat/Jacobs no longer offer replacement housings.

 

I could dig up the receipt, but with shipping was around $1450.00. I bought tune up kit and the control group (wiring and all switches) @ local KW dealer through Paccar parts a using Jacobs P/N saving money vs using Cat P/N's. Truck is a hobby truck, so all parts I inspected,coated with rust preventive, put in storage containers.
Your picture looks like the 349 series Jake. I asked about them when I bought mine and salesman said it is very rare to find a pair of housings that didn't have at least one worn piston bore on those. The 349's had 30% more braking HP @ 400 braking HP.