If you have clubs with Dynamic Gold steel shafts, can the Sensicore inserts be added later? If so, do they get installed down by where the shaft goes into the club head?

Aimee,
My last set of irons had Sensicore. It is a proprietary process that is added at the factory.
There is a product, I think they're called "Pro-soft" inserts, or something very similar, that can be added aftermarket to any shaft. I think most clubfitters would be familiar with the product. There is some sort of tool used to install them into the shaft, but I'm not sure if they go in from the tip or butt end of the shaft.
So far, I haven't noticed much difference in my non-Sensicore shafts vs. the sensicore.

Aimee: Golfsmith sells some vibration absorbing inserts that can be installed in your irons. They go in from the butt end after the grip is removed. Go in about to the end of the grip. Name is Vibra-X. cost is $9.95 per 6 inserts, so you'd need to get two sets. If they work as well as the Sensicore shafts do, they will reduce vibration about 70%. I don't know if they would fit inside a graphite shaft, as they are made to just fit inside a steel shaft. Would be over kill in a graphite shaft anyway. I have Sensicore shafts in my irons, and I like them guite well. Good for us old guys with arthitis and old bones.

Thanks, guys, I'm doing the research on behalf of hubby. He has tendonitis in left elbow and uses steel shafts on his irons. Thinking this might help him.

I'd say definitely go with the inserts. That's one of the main reasons for them. They reduce virbration more than graphite does. If he likes the ease of hitting graphite, he will like the inserts more.