I have since change some fluids that get overlooked on C4 corvettes. Many are not driven during the winter months or maybe only on good weather days. I recently flushed the radiator on my 1993 Anniv. due it having the original radiator. The overflow had a rusty looking antifreeze so that was taken out and cleaned. I then sent to a radiator shop Central Radiator in Pawtucket RI. and they did a flush for $110. Although I did not have an overheat problem it's still good preventive maintenance. I also flushed my brake fluid, if your brake fluid in the reservoir looks the color of Coca Cola you might want to do a flush. Easy to do, I purchased speed bleeders to replace originals and it's easier to bleed with only one person. Differential fluid is also another easy change that is sometimes overlooked that was easy to complete. My next change will be trans fluid and filter that I will send out to a transmission place. We all change our oil religiously and that is probably twice a year for a vehicle that is driven less than 2k miles a year for me. Living in New England the weather is not that co-operative. Once the Trans, diff, radiator, and brake fluids are change your good for few  years depending on use. 

It is great that you've done all this. I'm sure your C4 is much "happier" now that you have. And once you finish up the other fluids, it will be in great shape, like you said, for a good few years.

Keep up the good work!

Don't forget to swap out the power steering fluid.  If you're not up for doing the whole system just suck out the fluid in the reservoir and refill with new fluid.  Doing this every so often will get cleaner fluid into the system and keep it from getting really nasty.