Hm... it reminds me of fortress Maximus a bit. Usually toys have a brand marking under their foot or something of that nature, like the company name and the year the mold was created. It might be something from Plex or Bandai, just a guess.
The show is called Special Armored Batallion Dorvack The toys from this anime gave us RoadBuster and Whirl, that tank is also from the show
My goodness! I had that toy when I was much younger! Unfortunately, I have no idea where it is now! I recall the tank mode and the bot mode wasn't that "interesting" as compared to Roadbuster or Whirl! X)