Found these on a Thor board... might help:
"If it is the Trailer version it is on the tongue If it is the fifth wheel it is where the king pin attaches"
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"Yeah look on the frame right where the Y from the hitch meets the ladder section of the frame (drivers side). If not there look on the drivers side outside front above the storage compartment."
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But, it sounds like you already looked there.
"If I'm wearing long pants, I'm too far north" - 2oldman