The A-E ticket distinction stems from a time when individual tickets were required for entry into each attraction. At the moment, the only actual listing for what ride required what ticket that I can find is for Disneyland, 1972. It's not WDW, but it should give you an idea of what WDW attractions would have been A-E tickets.
Courtesy of yesterland.com:
A:
* Main Street Horse Cars (Main Street)
* Horseless Carriage (Main Street)
* Omnibus (Main Street)
* Fire Engine (Main Street)
* King Arthur Carousel (Fantasyland)
* Sleeping Beauty Castle (Fantasyland)
B:
* Main Street Cinema (Main Street)
* Motor Boat Cruise (Fantasyland)
* Swiss Family Treehouse (Adventureland)
* Casey Junior Circus Train (Fantasyland)
* Alice in Wonderland (Fantasyland)
C:
* Fantasyland Theater (Fantasyland)
* Mad Tea Party (Fantasyland)
* Autopias (Fantasyland, Tomorrowland)
* Shooting Galleries (Fronierland, Adventureland)
* Peter Pan Flight (Fantasyland)
* Dumbo Flying Elephants (Fantasyland)
* Mr. Toad’s Wild Ride (Fantasyland)
* Snow White’s Adventures (Fantasyland)
* Mike Fink Keel Boats (Frontierland)
* Great Moments with Mr. Lincoln (Main Street)
D:
* Rocket Jets (Tomorrowland)
* PeopleMover presented by Goodyear (Tomorrowland)
* Flight to the Moon presented by McDonnell Douglas (Tomorrowland)
* Storybookland Canal Boats (Fantasyland)
* Skyway (Tomorrowland, Fantasyland)
* Tom Sawyer Island Rafts (Frontierland)
* Davy Crockett’s Explorer Canoes (Bear Country)
* Santa Fe & Disneyland Railroad (Main Street, New Orleans Square and Tomorrowland)
* Columbia Sailing Ship (Frontierland)
* Mark Twain Steamboat (Frontierland)
E:
* Mine Train Ride (Frontierland)
* Pack Mules (Frontierland)
* Jungle River Cruise (Adventureland)
* Disneyland-Alweg Monorail Trains (Tomorrowland)
* Matterhorn Bobsleds (Fantasyland)
* It’s a Small World presented by Bank of America (Fantasyland)
* Enchanted Tiki Room presented by United Airlines (Adventureland)
* Submarine Voyage (Tomorrowland)
* Pirates of the Caribbean (New Orleans Square)
* Country Bear Jamboree (Bear Country)
* Haunted Mansion (New Orleans Square)
As of 1982, the whole ticketing system was abandoned in favor of all-inclusive passports. If I remember correctly, it wasn't unheard for an attraction to change ticket classification. From 1971-1982, I'm pretty sure that Country Bear Jamboree went from E to D or C.