Im sure they are repairable, sounds like the seals on the pistons are leaking, an internal leak like the tech said. but for that price sounds like it would be just as cost effective to replace rather than repair. Sounds like a repair I would do myself personally, but also sounds messy. Finding the correct piston seals might be fun, but im sure they would be availible, nothing else if you can yank the cylinders, sure there is a company that can rebuild them local to you.
Spencer & Tracie RVM#62
2013 RAM 3500DRW 4x4 Laramie, Cummins, 385HP,850FTLBS Aisin Trans
2014 DRV Elite Suite 41RESB4
Spare puller:2004 RAM3500DRW Cummins (DW's truck)