I dug out my kit after reading your comments. I've had it at least 3 years or so, but still haven't gotten around to it. I think I only bought it because it was my favorite tank kit from the old Matchbox 1/76 scale series.
Anyway, mine comes with the PE grill #7, if that's what you are referring to. It is bagged with the main PE fret with parts 1-6. The instructions and the side box art make no mention of the grill, nor does the PMMS review of the kit from 2006. http://www.perthmilitarymodelling.com/reviews/vehicles/bronco/cb35010.htm
The instructions mention using the resin idler wheels for a WW2 tank and the included plastic wheels for a post war tank. My "resin" wheels are bagged separately along with the tow cable string, but my "resin" wheels do not look resin, they look like they are made of the same plastic as the rest of the kit.
If they're resin, they are some of the best resin cast in olive green that I've ever seen. The box art side shows resin colored wheels along with the normal pour stubs that are also shown on the instruction sheet. My wheels do not have any pour stubs or even sprue marks. Terry Ashley's review (above) clearly shows resin idler wheels depicted in the instructions and box art. I am glade mine are plastic.
Bottom line, it looks like Bronco did some upgrades to the kit by adding plastic WW2 idlers in lieu of the resin ones and the PE grill.
Your "pre war" comment threw me too and I originally passed up this thread because of it. It was a very late war tank heavily influenced by the Tiger I captured by the British Army in Tunisia. Some think of it as the "British Tiger".