If your going to include the MI-10 (only has 8 ton carrying load) which is no longer flying then you should include the MIL V-12. which was designed to carry 25 tons, ended up carrying 40 tons. The Mi-26 is only 20 tons.
5 is an A model, not a B. CH-54A
The B model has a different rotor head/swash plate, landing gear, bigger horizontal stabilizer.