Where is the "HUD tag" you have found? Take a photo of it and post here and I will explain the information on the tag.
Manufactured homes are constructed to the HUD building code that went into effect 06-15-1976. When a HUD code leaves the factory a metal tag or tags depending on the number of sections is affixed to the lower left side of the unit as it is towed down the road. Occasionally they are at the lower left corner of the front and lower right rear when the siding is placed on the two sides after the unit is installed. Also at the same time a letter sized piece of paper is affixed somewhere in the interior that has a map of the United States on it, it states the location of the factory, date of it was manufactured, serial or vehicle number which is used in the documents for the chain of title and some times the same numbers that appear on the exterior tag. Those two items are extremely important and should never be destroyed or damaged from a manufactured home--all though many people do. Most manufactured homes have a steel undercarriage or frame that provides the structural support. Although around 1980 some were constructed completely of wood, without a steel frame/chassis for support.
Factory built homes are classified for lending purposes according to what building code was followed during the construction while it is in the factory. Once the home is complete it remains a manufactured home (HUD code) for the remainder of it's economic life regardless of how it is installed, what type of foundation it has, additions, modifications after it was built, etc, etc, etc. Quality of a manufactured home can be minimal or very high end--just like a car can either be a Yugo or a Rolls Royce.
Modular homes are constructed to a local site building code that should be in compliance with the site where it will be installed. Some manufacturers place labels and other documentation in or on the home that might be similar to the HUD label but a different color with different wording. Modulars can be constructed on a steel frame/chassis and are known as "on frame" modulars. "On frame" modulars are not eligible for Fannie Mae financing, although they are acceptable to Freddie Mac, FHA and VA. Modulars that do not have a steel support system are known as "off frame" modulars and acceptable by all lenders.
On this website are links to various information, check them out. You might be able to identify your property by the links that are provided on this report. I would be glad to see photos of the documentation that you find on or in the home, so feel free to post it here.