First Corps and Westwind are fairly upfront about being 1/48 and 1/60 respectively. Blacktree Design seem to be all over the place and some of their kits or as some would have it, misshapen puzzles, are huge the Universal carrier being a prime example.
I have a couple of different examples of Warlord and Rubicon kits (T-34 and M5A1) and they are pretty much identical in terms of proportions. I understand although I haven't measured one that Minairons' 1/56 offerings are pretty much true to scale.