ORIGINAL: Jim Thomerson
The diesel pictured is a G31 1.5 cc. There should be a rubber cap over the end of the backplate. I had one and though it a very good engine. There was also a similar G29, with red fins, at 1cc, and G30 at 2.5 cc.
Mine came without the rubber endcap also. Perhaps someone lost it while handling it in the hobby shop. Didn't affect performance. Still have that engine. Usta have ( [
] ) the G30 also. Traded it off back in the day.
George