Focus on the Family Radio Dramas (very well done, but abridged; I much prefer having children listen to these read first) Narnia series, Secret Garden, Little Women, Les Miserable, The Hiding Place, Ben Hur, Anne of Green Gables
Look for all of the chapter books in my list in audio versions; many are available.
A
Alexander, Lloyd

The Pyrdain Chronicles Box Set
Several books
Gender: B
Level: 3, 4
B
Banks, Lynne Reid

The Indian in the Cupboard
And sequels; one of them has some weird spiritual aspects—may want to skip that one
Gender: B
Level: 2, 3
F
French, Allen
Excellent boy stories!

The Story of Rolf and the Viking Bow
Gender: B
Level: 3, 4

The Red Keep
Gender: B
Level: 3, 4
H
Harrison, Michael

Don Quixote
A retelling of the Miguel de Cervantes tale
Gender: B
Level: 3
J
Jacques, Brian

Redwall
21 books, all in the series. Great boy books!
Gender: B
Level: 3, 4
Jefferies, Richard

Bevis, the Story of a Boy
Written in 1906
Gender: B
Level: 3
L
LeFeuvre, Amy

Teddy’s Button
Written in 17th century? republished by Lamplighter Publishing. Great boy story!
Gender: B
Level: 2, 3