Can I tow a 7,500 lb 29 ft. boat on a triple axle trailer (450 lb
tounge load) with a 2007 Yukon XL 2500 (3/4 ton) 4wd with the 6.0
motor (manufacturers towing capacity is 9,400 lbs.).  The hitch says
"5,000 weight carrying 10,000 weight distributing 600 lbs maximum
tounge load".

Howdy lakemead1-ga,

Most likely you are going to need one more thing in order to safely tow your
boat, and that is a weight distributing system, which is what is needed to
allow your hitch the ability to carry up to its full 10,000 pounds limit.  As
you mention, your Yukon XL 2500 is limited to towing 9,400 pounds, so you are
fine there.

The etrailer.com site talks about "Weight Distribution Trailer Hitch Systems."
http://www.etrailer.com/faq/aboutwd.asp

"A weight distributing system includes a receiver or hitch attached to the tow
vehicle, a hitch head mounted on a shank that fits into the receiver opening, a
spring bar assembly that fits into the hitch head, and hook-up brackets that
connect the other end of the spring bars to the trailer frame with chain."

From your description, you probably need the "spring bar assembly" mentioned on
the above page.  The above website has a drawing that shows the spring bar
assembly, and the Drawtite-Hitches.com website covers weight distribution and
sway control systems, with some nice illustrations as well.
http://www.drawtite-hitches.com/WD/weight-distribution.htm

"In addition to weight distribution you might also want sway control. Sway
control helps dampen sway caused by traffic and crosswinds."

If you already have an adequate weight distribution system properly installed,
then you are all set.  Otherwise, your hitch would not handle the load.

If you need any clarification, please feel free to ask.


Search strategy:

Google search on: 10,000 weight distributing towing
://www.google.com/search?q=10%2C000+weight+distributing+towing

Looking Forward, denco-ga - Google Answers Researcher