2011 Workhorse chassis, 18000 miles. When one shakes exhaust pipes, should there be movement where pipes join crossover, or should it have been torqued so they are rigid? Thanks
The exhaust connections should be snug with no movement "at the joints." The movement you can expect to see would result from the rubber bushings that are attached between the frame and the hangers that are welded to the exhaust system. In addition you should not see any movement where the pipe is attached to the exhaust manifolds.
The best way to check it is to have someone move the tailpipe(s) and see what moves.
Welcome to the forum. The connections should be fairly tight. There is enough flex in the exhaust system the engine torque should not affect the system. I would look for signs of gas leakage at the joints. If there is signs of leakage, either try to tighten the connection yourself, or have it done. Today's engines run very clean, that you will not notice a leak, as CO has no odor.
Most exhaust systems will move when you shake them. The reason for this is to allow flex as the engine moves due to torgue, otherwise it would break the exhaust pipe if rigidly mounted.