It fits together; that must have been GM's goal at the time. Its just one of those things that makes one wonder what they were thinking. The original transmission pan; has a drain plug, but yet the cross member prevents easy access to the transmission filter! It's a real mess to change both; the design made an easy thing into a really irritating drippy mess.
I've owned the car since I was 18 and still recall my thoughts the first time under the car............."What the "
Over time I've decided they got 99% of the car right, this is just something that could have been a better design on the cross member.