Do you have the front part of the cable anchored in the frame rail clamp? It's hard to tell from your first photo. It almost looks like the cable housing is in the clamp. Move that rubber weather protector out of the way so you can inspect the cable stay (metal end). I've attached a photo from an old cable that shows a machined groove that secures that end of the cable in the frame rail clamp. If there is a cable stay on the end, be sure it's in the clamp. The excess cable between the backing plate and frame rail clamp can be routed in such a way as to take up the extra length. Two inches is a significant amount to deal with; however, you have to be sure that end of the cable is secured in the clamp for the parking brake to properly engage.
Please post a photo of the cable with that rubber boot out of the way. I'd like to see what you're dealing with there.
