Pretty easy.The front,rear and bottom edges have a small lip that is folded over the edge of the inner structure,the top usually just slides over.To take the old one off I just grind off the edge till the seam splits and the skin pulls right off.To install the new one you just slip it over the shell and fold the edge over with a hammer and dolly or there are special crimping tools available,either way there is usually some dolly work to starighten the edges.Also make sure to fit th edoor to the opening as the skin does have some room to move around before you lock it in place with a couple tack welds.I would do a skin over a large patch any day!