55-57 2nd series question

[yellowGT]

My brother asked me to post this question up for him since he is interested in getting a 55-57 chevy truck. We are really wanting to know what the differences are from one year to another? We see the different grills but what else besides that? Anything else on the outside or maybe the inside that we might be missing? He really wants a 57 but ran into a great deal on a 56 so he is in a loop right now. Thanks guys.