Do NOT do the pac-brake ! Guys with commercial trucks have lost motors because of no warning when they fail !!! And I mean guys I know that are as anal on maintenance as racers are on their cars. Salvage yard units might be the best route for a true Jacobs brake , but the 11 liter is a long way out from being in use in numbers. I've done cross country a long time andin the past with 80,000 pounds in a commercial rig had many with no jake brake , just liken it to doing a 24 hour race , lift earlier , braking more gently . Also sometimes routing is a good way to minimize issues. Example : I 40 leaving Barstow Ca headed east , use old route 66 to miss the big hill on the way to Needles , 6 miles longer and MUCH easier on a rig ( Old highways generally followed rail road surveying and that meant avoiding steep grades) And getting into Kingman Az do the same , 2 very small grades to Seligman , 18 miles longer but much easier drive .
