His other known role is as the voice of Slinky Dog in Toy Story 3 , replacing Varney who died in 2000 ( and , according to John Lasseter , Clark sounds an `` awful lot like him '' ) . Ironically , it was revealed that Clark and Varney have known each other for a long time . Clark voiced Slinky Dog in Toy Story 3 , replacing Jim Varney , with whom he was a close friend ; Varney died in 2000 .