The extended cab looks funny to me because it is not normal looking therefore "funny" not that I laugh about it, just that it is unusual. I think if you stretched the doors to match it would probably look OK.
Basically I think that your eye should not be drawn to one particular part of a truck on first sight. All details or modifications should be subtle so you can take in the whole truck in the first glance and then start to notice the neat or well done things about it as you examine more carefully. I don't like to be shocked when I first see something, I like for it to grow on me.
That's just my opinion,
Grigg
