Wing tank myth and 3 wings
There are three RV-3 models out there. The RV-3 was the original design and suffered a few spar failures. The RV-3A is essentially a modified RV-3. It has some stiffers added but retains the forward fuselage fuel tank. The RV-3B is the current kit offering. It has a different wing, which includes leading edge fuel tanks, like the other RV's (RV-12 excluded). Also the fuselage fuel tank has been removed and the spar attach points beefed up, I believe.
This can be a complicated subject not rendering itself well to quick reply. If you've got an interest in the early 3, its probably worthwhile to budget some time for reading.
Wing tanks can be seen on type one, two or 3b wings. Check the registery at
http://www.romeolima.com Out of the less than 30 or so non-b's, I count 4 of them showing wing tanks and I've got a type one wing with wing tanks myself not on the registry.
The only wing and tank combination that would surprise me would be a 3b without wing tanks, but even then, it wouldn't be a real shocker if someone mated a modern 3b wing to an old 3 fuselage that already had the fuselage tank, and in the pursuit of simplicity, they leave out the wing tanks, and just keep the fuselage tank.
So forget fuel tanks for a moment. We have 3 wings: type one, type two, and 3b. There are two change notices (CN) that can be applied to both the type one and type two wings. However, a non 3b wing may not match any of the categories. Some of the early builders seemed to be aware of the wings problems, so they built in fixes. If they were building when the CN's were available, they likely incorporated those, but others came up with their own solution. Sometime in the last year or two, I recall someone writing in this forum about a 3 they were looking at with a one piece wing!
This can make pre-purchase a bit more work. If it isn't a 3b, one really needs to get a good look into the wing with the cn-1 and cn-2 documentation handy, so you can figure out what was done.