I don't have a psych degree or amazing advice but I do have a kid with a wide range - he maxed out 2 subtests and then got 5th%ile on another.  This was actually higher than the first round of testing that was done a couple years earlier where he got 2nd%ile on the same subtest.  I'd be impressed to see a wider range than that.  There isn't much room on either tail (but there is some...). 
He's officially gifted/LD. We see both ends of the extremes in everyday life with him which can be lots of fun at times.  Curious to hear what others say.