This past weekend I had to replace the endlinks on my 1993 Del Sol. The one side had completely broken off, 17 years old. While replacing both sides I notice how compressed and distorted the rubber pieces had gotten.
My question is now should I replace the ones on my 1999 GSR? If so should I use urethane or a different type of rubber?

 

When to replace? When the rubber is old enough to be visibly worn or deformed, or if it cracks.

Rubber or urethane? I'd go with rubber, simply because of how much deflection is required for the endlink bushings.

I think that most people who are that concerned about their ARB bushings, end up with spherical bearings instead of bushings, but those have a rather limited lifespan.

 

The endlinks on my ep3 are crap - one broke after an autocross (I also have a 20mm rear swaybar). I now sport a corsport endline and a stocker, so when I am unlazy ill replace the other but if youre on stock sway bars I wouldnt worry too much..