Be very careful with those tabs (one on each side) that hold the blower fan housing to the core housing, they break very easily especially when trying to get the housing in and out. It will take the better part of your day to do this job, unfortunately. Don't be afraid to gung-ho remove stuff, that is the general rule on the 164, remove as much as you can and it will become easier.
i noticed that when I removed the wiper rack a few days ago, that you can get to the left side of the heater core hoses and the tab on that side much easier than if it is left in place, so don't be afraid to move that out of you way too, it is easy to put back and will give you more room to move the blower box around and get to the hose connections at the core.
Charles
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'91 164L 5 speed 180k and counting
Chattanooga, TN - Home of the new VDUB factory!