I have a pair of 650's, a 550, and a SDB. Only the SDB doesn't have a light,, because of the design.
I can not say enough good about the light system I use.
I did a lot of "studying" before I ordered a "KMS Squared" light system, with (1) light strip & one switch. After I installed it,, and tried it,, I could not order the light strips for the other (2) Dillons fast enough. I use the light switch for all (3) lights. It unplugs from one & into the other.
KMS Squared is Veteran owned & operated smaller company. The light system carries a Lifetime warranty. They mount to the underside of the press frame,, & not through the center or other places. Out of the way,, easy to install & top quality.
They may not be the $10 cheapies found in some places,, but these are designed to be press specific. And they are not super expensive,, when compared to many others.
Check them out; kmssquared.com