Here is an important fact that @oceanbrave touched on.

You only get a fraction of the old trany fluid out with every drain.
That is exactly why I fill and drain it 2 more times, for a total of 3 flushes every time the trany fluid is changed.
To ensure you are getting:

1st flush: 5/11L = 45% = 5L old fluid removed, 7L old fluid still inside after flush
2nd flush 7L x 45% = 3.15 L old fluid removed, 3.85L old fluid still inside.
3rd flush 3.85L x 45%= 1.73L old fluid removed, 2.12L old fluid still inside.

With 3 flushes, you now removed 7+3.15+1.73 = 10L of fluid = 10/11 = 91% of the fluid.

Hope everyone understands that changing your own trany oil without a power flushing machine only ONE TIME is useless and waste of time and fluid.

 

The driver side of the trany oil pan gets hung up on the exhaust manifold or heat shield. It is a common problem with the H2. Not sure if all years affected?
Not think that it is related to the cats being changed. Although that could actually make it worse if you are dealing with custom bends in an aftermarket setup or sloppy install.
It is another poor GM design to route the exhaust that close to the oil pan. Asking for heat soak if nothing else.

A pry bar on the exhaust while the pan is being removed helps.
But that is one reason you want an empty pan. You are going to have to wiggle that pan a lot to get it out.
The oil should be hot when drained. So a drain allows you to do that without your arm getting burned on the exhaust manifold. Just drain and wait for stuff to cool.

 

finall echo what you're saying about design, just a fraction more clearance and removal would have been so much easier.

In addition, why didn't GM put in a drain plug?

Also there's the magnet, I recall the Dorman pan didn't have one, so I took the one off the old pan and fitted that - guess what, it went in the exact same position around the plug, it's as though GM decided to save a few dollars and not fit a drain.

The original magnet was super-strong and quite hard to pull off, it will never move and definitely required I'd say.

 

Yes, I too recall the magnet now. It is super strong and will definitely not move around at all.

I think maybe GM did not put in a drain plug to save a few pennies.

If the argument was that a drain plug was not needed since it is not serviced often, then that would be false. Why? Because it is the ONLY assembly on the vehicle which carries fluid that is designed to be periodically changed and yet does not have a drain plug. All the others do. Ridiculous.