This is the cover to Newton Comics' The Avengers #6:
It originally appeared on the cover of Marvel Comics' The Avengers 3:
The cover for this issue was later used as a poster in The Avengers #10 and The Deadly Hands of Kung Fu #1:
This issue contains one story: The Avengers Meet.. Submariner!, originally published in The Avengers #3.
This is the story which was skipped in Newton Comics' The Avengers #3.
The main instance of editorial modification in this issue occurs on the splash page:
The page is cropped at the bottom to accommodate the indicia. The banner at the bottom of the original page is omitted:
This scan is from my copy of Marvel Masterworks Volume 4: The Avengers Nos. 1-10, Third Printing.
This issue was published 20 September 1975. It is the first issue in the series to appear with a reduced page count from 44pp to 36pp and a cover price increase from $0.30 to $0.35. This change was effective 13 September 1975 in conjunction with the introduction of the Swap Cards.
The poster in this issue was The Amazing Spider-Man and the Human Torch, and the Swap Card was Spiderman (sic) Series A (1 of 15) No. 5:
The poster is adapted from the splash page to Have Yourself a Sandman Little Christmas! as published in Newton's The Amazing Spider-Man #2, and was previously included as the poster in Newton's The incredible Hulk #1. The Swap Card features the cover to Newton's The Amazing Spider-Man #5.
This issue carries in-house advertisements for The Amazing Spider-Man #8:
and The Incredible Hulk #6:
and Conan the Barbarian #3:
The Swap Cards Cometh Bulletin is also in this issue.
The contest expiry date is 3 November 1975.
This issue was advertised in-house:
Update 7/7/2019: Robert Thomas has sent me some photos of his rather bizarre copy of this issue - essentially a double-sized issue with two copies of the one comic under the one cover, including two posters and one Swap Card. A genuine rare Production Error Variant!