Thomas & Friends Trivia or Fun Facts Game

... so my prediction would total at 510.

OK, you've suggested 10 layers with 51 trucks in each. Let's do a simple check on the figure 51 first.
Your box base area is about 29cm x 22cm = 638 sq cm. Divide this by 51 and you get 12.5 sq cm. for each truck.
Given that just the body of each truck, without considering projecting buffers or couplings, is about 8cm x 4cm = 32 sq cm., you can see that you have a problem.