trying to break down some codes I found on the inside of the console door lid

WA-LS 743 U5743 10T
the car is dark blue, but I could not find any 28U code. Also it shows a KC4, but it does not have the heater hose like what is shown for a KC4.

the oil cooler, er, oil heater, has a housing that fits between the filter and the block. that housing has a hose that runs into the engine block, and one that comes from a hard line under the engine. It's a convoluted mess, if you ask me.

As for 28U, it is more than likely an internal control code, vs a real option. Many of the RPOs are more aimed at the assembly process than they are at actual options.

This is why the black book, for example, does not show many of these RPOs, because they didn't effect the outcome of the cars construction in a meaningful way.

For example, there are some codes that indicate power mirrors... well, every Vette got them. The the RPO for power antenna... same thing... or even an RPO for A/C, when call cars got it. But the option had to be shown.

10T is your Arctic white vert top......28U should be on there somewhere as a color code...Dark Blue metallic for your car...

that almost makes sense... code 10 is for white, so add "T" for top, and we get 10T for a white top.

Code 28 is the color for dark met blue, however, I can't realize a "U" meaning.

The number U5743 is a code for the paint color, used by by body shops to mix paint, IIRC.