I've read several reviews on Kaizen tracks and definitely wanted to try a set(or two) of the PzIII/IV versions. But,, at every on-line site I've searched, they're out of stock, back-ordered(2 or more months), or don't carry them. Where can I find a reliable source??? Thanks for any suggestions.

HobbyEasy has one set listed, but that's a Sherman set. You could contact them and ask if they expect stock eny day soon.
MS Models has most of the Kaizen sets listed. Text is in Japanese (ofcourse), and I didn't put the descriptions through a translator.
Also, I have never ordered from them, but surely others have
http://www.msmodelswebshop.jp/product-list/191

I have the Panzer III/IV mid, with slots if you want them. They are assembled to fit a jagdpanzer IV, but links can be added or removed. They go together well and have decent detail.

Thanks for the link, Theo! Matt, I sent you a pm.

I been getting mind on e-bay. The suppliers in China never seem to run out. Wish they had bigger selection, they are a very good product and the price is much better than metal tracks.

Mark