Auto populating date/time

Hi all, I am have created a appointment schedule in excel for a fleet of trucks. However, I need to figure out how to make excel recognize when a truck number is entered in the schedule and populate the current date entered into another sheet which lists the truck numbers.

For example, I enter truck 357356 into ANY cell inside the schedule and on the sheet labeled "Reefer" (refrigerated) it returns todays date automatically.

I have tried IF statements and it will work if the number is entered into one cell but I cannot not link all cells to that IF statement.

Here is the spreadsheet