Tonight the crossmember was removed; It was in extremely bad shape, with all of the bottom missing. Once it was removed though I found that everything around it is solid. It had even blocked rust from spreading to under the floor, for the most part. It’s apparent that the crossmember had been holding water, and because of this there are two rust holes in the frame where the frame met the end of the crossmember. These areas will be cut out and patched along with the hole in the heater tube.