The original rear shock absorbers on a TR6 are kind of a throwback design, as they're lever shocks and not the more common modern tube shocks used on pretty much every other car since the '60s.
This pic shows lever shocks on the left, tube shocks (as on the front of the car) on the right.
Since my car came to me with a tube shock conversion already installed, I never really experienced what the original ride of the TR6 was supposed to be. The rear end always felt brick-hard, and i originally attributed that to the age of the shocks, but when my brother and i installed a new tube shock kit it felt basically the same. Every little bump in the road made a rattle in the body somewhere, and the rear wheels would hop over anything bigger than a small twig. It was a little tiring, but i chalked it up to being a sports car.
However, some recent chat in some of the TR6 message boards talking about the difference in ride quality between systems got me thinking about the switch again. A lot of the opposition to tube conversions is the risk of frame damage, because of the change in forces on the shock mount to the frame. This can definitely happen, but my frame is pretty solid, and i don't drive it hard, so i wasn't terribly worried about problems in the near future.
I got rebuilt shocks from World Wide Auto Parts in Madison, with new shock links and limit bumpers from other suppliers. It's a really easy swap, entirely done within an hour or so of bolting in parts.
On the first test drive the ride was immediately a lot nicer. Even with the heavy duty springs in the rear, it's a lot softer over small bumps now. It was almost floaty-feeling at first, but that's mostly in comparison to the old system. It feels like the rear suspension is finally doing something, and it's a lot more pleasant to drive.