I think J-Hulk is right. I read recent reviews of the new Stug release from Dragon, and it's as you describe it, some photoetch, plus turned aluminum barrel. I haven't heard of anything of the sort from Trumpeter, and I tend to stay fairly up to date on their stuff. They haven't released any WWII German armour yet in 1/35, (except the Leopold
) and I haven't seen plans for any releases this year either, except the Morser Gerat, another railway gun.
I think you're probably referring to the Dragon kit...