Several... MANY of us with the 85 mph speedo have change them out for a 140 mph speedo and most of us have used Red Line Gauges. A little phone call to "John" (owner and operator) of Red Line Guages convinced a whole herd of us to make the switch.
Here are a couple of past Threads about the conversion. The second one address's Auto Transmission Questions
looks like this red-line guy is out of business. just called, disconnected. if you have any input on corvette central, let me know, i'm leaning towards them. i would hate to get burned, and i dont think they want a 300 lb man on their doorstep. hehehe
I probably spent a good hour or so just BS'ing with him about stuff in general on the phone,real down to earth guy,one whom that after talking with him,you feel like you have known him for a long time.
I too definitely recommend John. I think I was one of the first couple people from the CAC to have a conversion done by him. I went from the 85 to the 140. I was looking at doing the 165 unit, however there were two things that swayed me.
One was that the fonts between the tach and speedo were different. Or, they was a similiar font, but it just didn't look right with all the numbers crunched on the face.
Two, I had heard that the greater the range of these old mechanical speedos, the less accurate they are at given ranges. I don't recall if it's it's at the high or low speeds (or maybe both?).
Yeah, it would be nice to know how much above 140 I'm going, but I don't spend enough time there (*teardrop*) to warrant the 165 speedo. The 140 suits me fine. (I already know that I cap out around an honest 155mph.)
I also recall that any of the major vette places wanted like $300 or something and John was doing the same or better job for like $100. And anyways, the vette places usually send out there stuff to a third party anyways. I wouldn't be surprised if John is the one that does 'em, but due to contractual obligations, can't say that. I know that MidAmerica or Ecklers or whomever contracts out their steering wheel resto-service, so I figure they probably do it with other conversions as well.