New details of the special episode - first announced last week (July 18) - were revealed at Comic Con 2013 by Rich Appel, currently a co-exec producer on Family Guy and formerly a producer on The Simpsons.
"[The crossover is] gonna be the season premiere in a year, but it's a super-sized episode - it may be an hour episode," said Appel.
"We were thrilled - [The Simpsons voice actors] Dan Castellaneta, Julie Kavner, Hank Azaria, Yeardley Smith, Nancy Cartwright... they all play their parts."
Appel explained that the special - which will air as an episode of Family Guy - was penned by the Family Guy writing staff, with just "two notes" from Simpsons execs Matt Groening, Al Jean and James L Brooks.
"As soon as Dan opened his mouth with his first Homer line, there was a wave of applause," Appel said of the first script read-through. "[And] there may or may not be a 5-minute Chicken fight between Peter and Homer!"
The Simpsons will also crossover with another Matt Groening creation - animated sci-fi comedy Futurama - in an upcoming episode.
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Watch a segment of the Family Guy Comic Con 2013 panel below: