NASCAR Racing: nascar qualifying, maximum ammount, mising

Question
Ive made numerous requests for this info, hope you can answer!
Why and when was 43 qualifyers introduced?
(not 42 not 44 just curious)

Answer
for a number of years 42 was the maximum ammount of cars in a race, then in the early 90's, Richard Petty, failed to qualify at richmond. It was a shock to NASCAR and its competitors that its greatest champion coudn't make the field. the following year the field was increased to 43. the 43rd spot is the Champions Provisional. that means that the most recent champion gets in the field. this was done in sirect response to Petty mising the field at Richmond the year before.