dui guy hit my truck dv?

On July 17th, a drunk driver hit my parked 98 4Runner. I wasn't in the vehicle. After finding out that the other guy's insurance company was out of state, I decided to get my truck fixed by my insurance company which has turned out to be a nightmare. I am still not completely satisfied with the work done and the claim is still on-going 3.5 months later. Since then, my new job is offering to purchase a new car for me and I took my truck in to get valued for a trade in. Aside from the "we don't want it" offers, I did get offers around $5000 which is about 9 less than a conservative blue book value. All this made me do some searching on the web. I found a lot of information on diminished value and am at that point of wondering what to do next. I have talked to both insurance companies and just the word "diminished" makes them tighten their lip and become extremely defensive. After reading some of the responses in the forum section, I am hoping someone can steer me in a positive direction.