Buy the house. If it means sell the truck, do it. A house - in theory - will appreciate in value and a truck won't. You will lose money on the truck, but not that much, I think. I'm guessing you're looking at payments? If you want to get creative, there are possibilities out there to keep the truck and the house. Look at a balloon loan on the house. You take a loan that only requires interest payments, then in about 7 years, you have to pay off the whole thing. At some point along the way, you refinance to a regular mortgage. Or 15 year mortgage or whatever. Finance the house and roll the truck payment into the mortgage. In the long run, you'll pay a ton more for the truck 'cause you'll be paying interest for 30 years on the **** thing, but it's an option. Buy the house, take a second on it to pay for the truck. That way, the "truck" payment is tax deductable. Do you have any relatives with money who would be willing to hold the note on your truck? Maybe you could work with a bank to arrange financing on both the house and truck so that you could reduce your truck payments for a year, then go back up to where you can afford it.
There are options. Of course, you'll pay in the long run since what you're doing is using someone's money for more time, but you have to decide what it's worth.
Bottom line - if this is your dream house, get it. Vehicles come and go. Homes are long term and, well, HOME. You're not planning on living in your truck are you???