Ken,
3.73 gears will fit in the Dana 36. I just converted my 2.59 to 3.54 and I'm very happy with them. A number of people have gone to 3.73. The caveat is that if you drag race the car the Dana 36 won't hold up to the abuse or if you make serious horsepower upgrades. For the Dana 36 what they do is use what they call a thick gear. This makes the the ring and pinion line up properly in place of the 2.59. It's a tight fit but it works.
Steve,
There are a few companies that make the 3.54 and 3.73 thick gear setups for the Dana 36 for your Vette. The most used one I've found is Richmond. I went with Strange (US Gear). I like them. There is also Precision Gear as has been noted. I beleive you may find Yukon has a package and Motive. You can't get a GM gear set though unless you convert to a Dana 44. If you want the whole Dana 36 pumpkin already built and ready to go in you can get one from MAD, Zip, etc.. I opted to not do that because of the cost, about $1,400. Search this forum for gear change and you'll find a rather long dissertation I did on gear swap on my92. I only did it a month ago.
Graham