I think what you mean is the version of the modules. The chassis is typically the same for all of them, the modules have a v1 and v2 generation.
v2 modules have different part codes, so if you run
show module
You can see the part numbers, and verify this in the HP online configurator (select 5400, then use module dropdown list)
http://h17007.www1.hp.com/tw/en/products/configurator/index.aspx
Or just google these Jxxxx numbers and read the product title (check if v2 is included)
Hope this helps,Peter