I hope I can clear up some of the confusion on Sundowner models.  The 720 and 725 models have been and are present models that are ALUMINUM FRAMED TRAILERS.  The 727 model was originally a Valuelite model that was built from late 1997 to December of 2007. 
All 727 models built up to January of 2008 were steel framed.  An easy way to tell the difference is either by the Vin tag as previously mentioned on this thread, or by looking at the bottom rail of the trailer.  If the bottom rail is covered in stainless material and is beveled, it is a STEEL skeleton trailer.  If the bottom rail is ribbed aluminum and not beveled (or angled), is is a ALUMINUM skeleton trailer. 

The person that posted that he has a 2006 727 Aluminum framed trailer is going to be able to tell by what I have just posted, or if he reads the last of his vin and it is either ZA and 4 digits or HA and 4 digits; he has a steel framed trailer.

There are also a couple of other ways to tell if your trailer is steel or aluminum framed.  Pick up the floor mats and look at the floor planks. They will be aluminum in both the steel and aluminum framed trailers, but the 720 and 725 models use an interlocked planks that run cross ways in the trailer.  The 727 models use a deep ribbed interlocked plank that run lengthwise.  They have about a 1" deel drain channel in them.

The neck structures are also different.  The 720 and 725 models use an A framed neck that is webbed with smaller tube steel, and makes for a "pie crust" look.  The 727 also uses an A frame, but the use angles across the neck from side to side.

If you have a manufactured trailer from January 2008 or newer; ALL Sundowner models will made with aluminum frames.

Hope this clears up some of the confusion.

I hope I can clear up some of the confusion on Sundowner models.  The 720 and 725 models have been and are present models that are ALUMINUM FRAMED TRAILERS.  The 727 model was originally a Valuelite model that was built from late 1997 to December of 2007. 
All 727 models built up to January of 2008 were steel framed.  An easy way to tell the difference is either by the Vin tag as previously mentioned on this thread, or by looking at the bottom rail of the trailer.  If the bottom rail is covered in stainless material and is beveled, it is a STEEL skeleton trailer.  If the bottom rail is ribbed aluminum and not beveled (or angled), is is a ALUMINUM skeleton trailer. 

The person that posted that he has a 2006 727 Aluminum framed trailer is going to be able to tell by what I have just posted, or if he reads the last of his vin and it is either ZA and 4 digits or HA and 4 digits; he has a steel framed trailer.

There are also a couple of other ways to tell if your trailer is steel or aluminum framed.  Pick up the floor mats and look at the floor planks. They will be aluminum in both the steel and aluminum framed trailers, but the 720 and 725 models use an interlocked planks that run cross ways in the trailer.  The 727 models use a deep ribbed interlocked plank that run lengthwise.  They have about a 1" deel drain channel in them.

The neck structures are also different.  The 720 and 725 models use an A framed neck that is webbed with smaller tube steel, and makes for a "pie crust" look.  The 727 also uses an A frame, but the use angles across the neck from side to side.

If you have a manufactured trailer from January 2008 or newer; ALL Sundowner models are made with aluminum frames.

Hope this clears up some of the confusion.

 Flooper; the frames on Sundowners were sprayed with a Canadian made undercoat treatment starting with 2003 models.  They were powder coated first and than undercoated on top of that.  It is a different material than the Suncoat that is used on the necks and the horse area.  Starting with 2003 models, in addition to the undercoating, Sundowner went to stainless steel hardware, and made LED lights standard equipment.