One test that you can do at home that might be interesting is to time his handwriting - have him write the alphabet, upper and lower case, and see how long it takes him (measure in letters per minute). You can google letters per minute vs grade level and get an idea of what is considered typical (although just a warning - there are a lot of different ideas re what is "typical" for handwriting speed). Sometimes kids with dysgraphia will have legible handwriting but it will be incredibly slow relative to peers.
FWIW, personality can play a role in how a child would do with this type of test as well. My older dd, who was tested on the WISC-IV at 7, had much lower scores on the entire PSI index and the block design piece of the PRI but is not 2e. My other dd is and her stand out lows were the entire PSI and WMI.
My older one would have done poorly on a test like polarbear mentioned above not b/c she is dysgraphic but b/c she was highly perfectionistic, meticulous, and had anxiety issues related to things where she was pressed on time when she was younger especially. She had a 19, 17, 8 split on the PRI with block design as the 8 b/c she froze when they told her to do it as quickly as she could over and over and wouldn't even complete the test. She never finished math minute timed math tests b/c she'd stop to erase and rewrite her answers b/c they weren't neat enough.
I do think that this one child of mine is a slower processor in relation to her other abilities, but I don't think that she is truly 2e. It wouldn't hurt to investigate further, but I wouldn't get totally stressed about a 2e type of thing just yet. It maybe that there is something else going on, it may just be personality, disengagement or something else that requires a change of teaching but doesn't necessarily indicate a LD or other disability.
