I have also done several 19's, 17's, and several from past years of all different chassis, as I'm sure several here have. Speaking to the G4's, the 19's all took about the same to make them line up under load. The 17's took a bit more work and shims to get them to align. Belt temps have gone down on all dramatically compared to previous. One of the biggest and best differences is the changing of the torque stop. This has been consistently poor from the factory for years on all the previous chassis' as well. I haven't seen an XP or XM come through the shop yet that actually had the torque stop down on the rubber pad as it's suppose to be. While my opinion is that it should be on the pad is just that, it is also what is stated in the shop manual for all summits. All of them I've seen are all the way up from the factory giving them the most movement allowing the engine to rock and tearing the motor mounts apart prematurely. Same holds true for the 850's, too much space in the stock torque stop allowing too much movement. The pre-loader though does allow you to remove this space though to get the alignment right for running under load. I realize that they are trying to reduce the vibrations from the engine into the sled and bars for a more comfy ride but as for performance it's a disservice to the customer ultimately costing them more money down the road in belts, clutch parts, and motor mounts. My .02...