I found this site while fishing for ideas, as my son was getting bored with his 6743. We really liked this pick-up: http://www.mocpages.com/moc.php/313976, but it was not sturdy enough for my son. I decided to strengthen the bed sides, but needed some parts from the cab, one thing lead to another and in the end I made a new design, keeping just Peteris Sprogis's clever idea for attaching the bed sideboards. It is not nearly as nice as his original design, but it can handle rough play. Your kids may like it, too. It is also fairly efficient, just three pieces left :-).
About this creation
It has a traditional construction: chassis, cab and bed.
However, I found that for a child it is easier to build it as a whole. Here's instructions in three sheets.