Docking / Port Replicators

Hi All,

Since there aren't much in the way of specs or other differentiating information from Dell on the Products page....

Anyone know the difference between the E-Plus Port Replicators?

Dell P/N:
7G37R, XGWJG, and the CP103 

Have some E5xx0 Lats to dock. Not had much luck with these in the past 5 yrs or so....

Thanks,
Jeff