click on the link below and will give you a brief description of what they are and do.......... http://opentrackerracingproducts.com/rollerperch/ read their FAQ's regarding roller spring perches, how they work and whether or not you will notice any difference etc.......... I have them and I am very happy!
Unless you'll be autocrossing the roller versions really aren't necessary... The rubber ones were fine for years and orig are still in my Fairlane, I'll likely be replacing them with the Scott Drake pieces...
anything you can do to reduce friction, will allow the suspension to work better, now whether or not you want to pay that much for roller spring perches.......go read their FAQ's and you can decide! I am very happy with them........ I have all of Opentracker roller products on my 73 Comet, along with higher rate springs, Koni Shocks, front/rear sway bars and yeah, I can really feel the difference in how the car handles, compared to non-rollerized stock bushing type Upper/Lower control arms and perches. FYI, I installed the roller spring perches first, just to see if I would notice any difference and yes, there was! Then, I installed the Upper/Lower rollerized control arms and again more improvement, but not as noticable as when I did the spring perches. All comes down to what you want to do or have your car do.........
Roller spring perches are hand built, John (Opentracker) starts with Scott Drake regular perches and then modifies them to roller. Nice thing about them, will literally last forever and can be rebuilt by changing the sealed roller bearings. Never have to worry about greasing, squeaking........
The Scott Drake pieces are still 'bushed', not roller bearing units. From the Link: These are made with synthetic elastomer bushings which are similar to polyurethane I bought a set from Opentracker for my car. One less area for squeaks and binding...
Here is some links from the past that may answer a question or two http://mmb.maverick.to/threads/roller-spring-perches.66359/ http://mmb.maverick.to/threads/roller-oem-front-suspension-conversions.49471/