Cladwood is a brand of a product that came to be generically known as hardboard siding. Regardless of who supplied this type siding to home builders the products had many problems. You can visit Cladwood brand on the web at
http://www.landmark-products.com/cladwood.html
An excellent alternative to hardboard is a product called T-111 (pronounced Tee One Eleven). It is not a composition product but a treated exterior grade plywood. Usually you can find a T-111 replacement that has the same look as your original hardboard, or so close that once you paint it will be difficult to tell the difference. You can find or order this product at just about any lumber yard
The down side is that the T-111 is more expensive. If you do elect to go with hardboard the way you install it will determine how well it will last. Hardboard type products do have an effective weather proof face. The problem arises in the way that the product is nailed to the home. Be sure that your nail heads are perfectly flush to the face surface, so that once you paint there are no small places where rain or moisture can seep through the nail holes.
The original Hardboard siding was fairly effective and a very economical siding alternative. Many of the extensive problems that have been reported over the years, in my humble opinion, resulted from poor installation standards. In most MH factories the installers air nailer is hooked to a master compressor shared by all the workers in the shop. Unlike using individual compressors, it is more difficult to regulate the degree of penetration of the individual nails. So some are shot past the siding face leaving a small area around the nail head where water can get past the weather proof facing. You may find other nails that are not fully driven... the head sticks out of the siding just a small amount. This leaves nothing to prevent moisture from seeping in around the shaft of the nail.
Once you have replace the affected sheets of siding be sure to give the entire home a heavy coat of paint, paying particular attention to the nailed areas, being sure to paint over all nail heads and any tiny breaks in the surface.
We have five hardboard homes in our park and we have them on a three year re-paint schedule. We also added gutters around the roof to prevent rain from running directly down the siding. This has prevented some of the worst problems we have seen elsewhere.