I'd say the first instance of "Stealth Force" would be the original 1984 Optimus Prime toy, because there's a square-shaped hole on the top of his trailer where Combat Deck's attack tower can protrude from - giving him an attack vehicle mode (pic <--2nd one from the left)
There were several Transformers in 1985 who could attach weapons in their alt modes; even the Dinobots had weapons in their dino modes (Swoop prominently uses his attack dino mode in canonical appearances). Jetfire has the most decked-out attack alt mode (and attack robot mode). But I'd say out of the Transformers in Devastator's year, the two Transformers that have the most "Stealth Force-esque" attack alt mode would be Perceptor and Tracks, because they actually transform into their attack alt modes rather than just sticking weapons onto them. In fact, Perceptor's tank mode doesn't require any additional weapons, he just transforms into it!
But I do like how Devastator's vehicle weapons are made up from his gestalt kibble rather than being separate accessories. Feels more resourceful to me.![]()