I got mine through a parts distributor at work. I did get a discount, so I guess I would have payed more than $150 without discount. The walbro pump I took out of the truck had a thick foam pad that went around it to take up space as it was a smaller pump. I thought the foam would be a good idea for the new pump but it wouldn't fit in the pickup bracket with the foam on it. That tells you about the size difference.
I thought about the no fuel in the return line comment too. If that is the case then you should have massive fuel pressure in the fuel rail. I would imagine the truck would run rich, and maybe even smoke. Hows your mileage. Otherwise, the pump would be not pumping enough fuel to even necessitate the return line, and I can't see how the truck would run. Double check that you indeed checked the return line and not the vent line