GM Chevrolet Avalanche - Manual (Page 145)

To replace the drain grate do the following:
1. Line up the clips on the vehicle with the slots in
the grate.
2. When you are sure that the clips are aligned with
the slots, push the grate down firmly.
The grate should clip into place. Don’t force the grate if
it won’t clip into place; realign the clips with the holes
and try again.
Side Rail Channels
The side rail channels are located on top of both sides
of the cargo area. You may want to flush them out
with clean water if you notice any debris collecting inside
of them.
When loading cargo into the cargo area, be careful not
to damage the rails.
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