OK- so here's the deal.
Not all drums are created equal, some open top drums might accept a Weber lid, but unfortunately none of the 55 gal. I have do.
So I created the soon to be patented Weber Flange Mod!
I cut the lip off a donor kettle and set it in the open drum. Some but not all fit securely, but mine do. Some here have used gasket material or just bolted them onto their drums.
I've made them for closed drums-the flange helps keep drippings from flowing over the outside of the drum and make a secure fit for the Weber lid AND various rotisserie ring setups.
Here is REDRUM with the flange mod and the EZ-Que ring
FUGLYDrum with the flange and the Weber ring
REDRUM with the Cajun Bandit Reversible Rotis ring
I use only square spit rods and round the edges that rotate on the rings down on a grinder.
Stay away from round stock, unless you flatten the spit fork thumbscrew points (Rib-O-Lator, Char-Broil Baskets too) on the round rod.
The EZ-Que/Weber cradles use round stock and I sometimes use a ferrule to keep them from coming loose from the motor.
Works for me, and I just remove the flange and can use the drum lid the way it was meant to.