Hints for the clue that begins, “Some treks through…”

1st part

When you find the license plates attached to the left post of Tow Mater’s sign, there are four plates, but you only need the first three. There is a character on each plate that is illuminated in the clue, some are numbers and some are letters. In many cases, when you are given a number but need a letter, you might try a simple replacement cipher, where the number stands for the corresponding letter in the alphabet. But also, some numbers look like letters, and if you’re trying to spell a word, you might think of what letter the number looks like. Not in all cases, but perhaps… one.

2nd part

Once you find the eye chart inside Flo’s Diner, you’ll notice it has lines and it has letters. The lines are numbered, but using a line/letter cipher, you might see the decimal numbers not as a single number but as two numbers with a separator between them (the period). For instance, the number 5.4 might be referencing line #5 and letter #4 (which is the letter “V”).