Well crap! We broke down 10 miles West of Jordan Valley, OR, last week also with a leaking hydraulic line. I noticed the problem when both the engine (C-12) and transmission started overheating. The engine temp got up to the 220s and the transmission up to the 210s. We unhooked the toad and limped into Jordan Valley. The problem in Jordan Valley is that there's no phone service other than T-Mobile (we have Verizon), therefore no internet service. Fortunately, Skinner's Coffeeshop had free wifi that enabled me to make wifi phone calls. After several calls, I found a firm in Payette, ID, that sent a tech the following day to make repairs. The total cost was nearly $3,000 - almost $700 mileage for Payette to Jordan Valley, Jordan Valley to Marsing, ID for a $280 hydraulic hose made by NAPA, Marsing to Homedale, ID for an air line boot, back to Jordan Valley (and the tech's return to Payette), and $204 for six gallons of Dexron III ATF. The good part was that we were back on the road in 24 hours.
The Marquis has been out to Freightliner Northwest in Hermiston, OR, today to have all the hoses checked and replaced, if necessary... another $1,000. Get out your credit card!