An interesting piece. In the Pre-TF version, the diecast back end had a hole in the back where the back-mounted gun fit into. This hole in the diecast (and the corresponding plastic peg on the gun mount) was noticeably smaller in the Japanese and intial Italian Pre-TF versions. In the Hasbro version, this hole was enlarged. We are still looking for a Hasbro version with the small diaclone hole; some theorise it exists, but like the Powered Convoy head, it may have been changed prior to its American debut. For more information on later-issue Hound mold-changes, visit the Autobot section of the site.
Here's some pics of the Japanese version:
And of-course the Italian Diaclone version: