Depending on exact ship dates of this issue and Grimjack 26, this is either the first or second full color TMNT story. However, Grimjack is the first drawn by Eastman & Laird as Richard Corben drew the color story in #7.
Reprinted in Teenage Mutant Ninja Turtles Color Classics #7.
Collected in Teenage Mutant Ninja Turtles: The Ultimate Collection HC Vol 1.