NewsOK.com has a great interview with Peter Cullen. Peter discusses the writing of the movie and some details of his audition process. It’s a great read.

Some great quotes -

“The script assistant was there, and she started reading for Ironside,” Cullen said.

“I said, ‘Excuse me, dear, do you mind if I read it?’ Because I actually played this character.’”

Cullen completed the read-through reading for both characters.

and

“(The filmmakers) were thinking more Hollywood big names,” Cullen said. “They did start to consider the original voice actors because of the enthusiasm and the … stubbornness of the fan base. God, I’m grateful for those guys,” he said.

Read it here