The AFCO's are great, the roller bearings are nice and smooth and everything is well built. I was really happy with the quality. And they offer replacement parts, should you want to change your roller bearings etc. I've also been really happy with the AFCO springs, not nearly as much sag as the Mopar XHD's I put on my Challenger. Only beef with those is they came plain, and I should have painted them before I installed them. But really that's my fault, I obviously realized they weren't painted.
The Calvert sliders look to be just as good though, and they have the angle built in. Now, it's a generic angle, so it won't be perfect either, but it would be closer than the AFCO's mounted flat. Somewhere I'm sure there's an equation for that angle based on the spring length and the relative mounting height of the front and rear spring eyes.
