I tow a 9,000lb Airstream trailer with a 1998 International "box" truck powered by the T444e Navistar engine. The transmission is an Allison AT545. Until now, my only complaint is that I should have bought a truck with more guts -- our 4700 was built for urban deliveries not over the road use. Recently, my transmission has become reluctant to engage reverse. Shortly after recognizing that problem, I noticed it was shuddering in reverse. The shudder is a low power thing and disappears when I apply more power. Other than that, the transmission seems well behaved in the forward gears. I was 3 service intervals overdue for fluid and filters when I took it in for a diagnosis. The tech found the fluid to be in "poor" condition and "swirly with metal and a lot of clutch material". But again, a fluid change was horribly overdue at this point, an accumulation of gunk was to be expected. A test drive showed the electronic modulator to be working properly. The pressure test saw: 30 psi reverse signal 30 psi main pressure in reverse 150 main pressure in neutral and forward They concluded that I should spend $3,200 to have a Weller remanufaction unit installed. Money is scarce. I can manage the transmission problem for now, but I wish I could have gotten them to speculate on what's going on inside that tranmission. That sludge, for example, is the accumlation of perhaps 3 service intervals. Were they keeping that in mind when the pronounced my transmission effectively dead? A thorough flush might be expensive, but it might be a good investment if it produced an improvement or at least a little more information? Perhaps I can squeak a few more thousand miles out of it. I'd appreciate any knowledgeable opinions. Thanks in advance, _Mike Allison AT545 behind a T444e Navistar in an International 4700 pulling a 9,000lb trailer.