So I have heard a few times that GW tournaments allow conversions, but only if the product is from 40k or WHFB. I have been curious lately about units that dont have models. Specifically Thunderwolf cavalry. After seeing yet another amazing mini for TWC on a site, I started wondering if the only way to use them in a tounry is to use the GW wolves with marines on them.

Can anyone confirm or deny this?