These blue Q8 sleeves from A&M resembled the graphics on many of their LPs.

This is the original green Apple "Quadrasonic-eight" sleeve used for the original release of John Lennon's IMAGINE, which has a lime green shell. This was the only release on Apple to use this green sleeve.

This gold sleeve was used on all Apple Quad 8 Tracks, including later editions of the IMAGINE Q8. These Q8's were all of the purple Capitol variety. (Announced but unreleased titles included the "Ringo" album and Yoko Ono's "Fly")

Most of Asylum's Q8's, like their "sister label" Elektra, came in these orange sleeves. Note the slightly different "Q8" logo on these as opposed to the orange Elektra sleeves. Carts in these sleeves were day-glow orange, with yellow labels. Real attention getters! The later issues were in the purple sleeve/purple cart combination and shared the markings with Elektra, as shown below in the Elektra section.

This is the original green  Capitol Q8 sleeve. It was used primarily on demo cartridges and on the early sampler tapes from  artists like the "Sounds of the Seventies Orchestra". Like the Apple Imagine tape in the green sleeve, the Q8's in these sleeves were lime green!

This gold sleeve was used on all of the major Capitol popular releases, and the tapes found in these sleeves are in the familiar purple shells, made by "audiopak"

Much like the COLUMBIA sleeves, this gold sleeve was used for tapes sold outside of the USA

One of the most familiar sleeves to adorn the Q8 section of a '70s record store, Columbia issues a huge number of Q8s, dwarfing all other manufacturers. Columbia tapes found today will still sound amazing, if found in good condition.

Most of Elektra Q8's, like their "sister label" Asylum, came in these orange sleeves. Note the slightly different "Q8" logo on these as opposed to the orange Asylum sleeves. Carts in these sleeves were day-glow orange, with yellow labels. Real attention getters! The later issues were in the purple sleeve/purple cart combination and shared the markings with Asylum, as shown below
 

This later dark purple sleeve came on the last releases from Elektra and Asylum. They were made to match the purple audiopak cartridges.

Since EPIC is a subsidiary label of the Columbia "group", their sleeve was identical to the Columbia and CBS sleeves.

Many labels used GRT to produce their Q8 tapes, including ABC, Arista, and Fantasy. These carts were blue, and sold in either the sleeve shown above, or a plain blue sleeve with no quad markings at all (not shown)

Carole King albums were released by ODE on Q8. The London Symphony Orchestra double tape was also released on Q8 by ODE, and comes in a specially designed box.

Project-3 released some spectacular instrumental quad 8 track tapes. This sleeve is the more common issue.
 

Here is an example of another version of the Project-3 Q8 sleeve.