this is the thread for toys that you can consider a sort of pre-MechTech Examples: Wreckage/Bludgeons sword guns TF1 - Bumblebee gun dagger PCC minicons
How are you defining MechTech? For really being the first of the new Transformers to emphasize weapon playability and exchangability, I would have to think Recon Ironhide.
If you just mean the 5mm peg it goes back to g1. The 5mm peg that mechtech uses is as old as TFs themselves pretty much.
Oh oh oh! I've been waiting to tell mention this. Deluxe Jazz/Smokescreen has the giant gun in vehicle and robot mode.