Phred, if we pay nothing for them, then we take a chance.... some good some bad.
I got 20 mc33033 chips, and I don't know what they really were but they were not three phase motor driver chips... thats for sure.
I have bought 100 lots of 4110 that ranged from 3mohm to 90mohm....... you get what you pay for..... but if you persist you can get a good seller that gives you what you paid for.
If you test them all, you find the voltage is always about right, but the rds on is the problem.
I suspect they make them, and sort them... those inside the parameters are real 4110, and those that aren't are usually called a different part number.... in these cases, they kept with 4110.
pay lots and get it right or pay very much less and take the chance... I do the latter, as after they are checked, in a lot of my applications, derated fets are fine for a lot of other jobs that don't need 3mohm rds figures to be perfectly satisfactory.... ie use the 3mohm in the big inverters, and the lesser ones in other projects.
.................oztules