I don't think it is a wideblock. I guess the next thing to do is find a spare 2g trans and see just how far off it is. But if you look closely on the picture I posted of my flywheel you can see the similarities between the two patterns. The only difference I can tell of is the bottom right bolt hole is in the wrong spot. The top right bolt hole which has the dowel pin is in fact on the 2g 4g63/4g64, just not with a dowel pin. If you look at these pics from Project Zero G, you can see the difference between this blocks bolt pattern (which is the same as Evo 4-9) and the the USDM 7-bolt's. Once again, the only difference is that lower right hand bolt hole and dowel pin.
Here's the Evo 4-9 block which is the exact same bolt pattern as my "newer" 4g64.
Here is the USDM 7-bolt (found in DSM's)
I think it's safe to say this is a minor road bump. With an adapter plate and a DSM starter plate it will bolt up just fine.
So I'm juggling idea's right now on how to solve the issue with the one bolt hole being off.
First idea: Install the trans with 1 less bolt and bore the hole where the new dowel pin will go. This would be the easiest and cheapest way to do it. This might not be the optimal idea for the really high horsepwer drag cars as the trans could use all the support it needs under 600hp+ launches. But with case hardened (or even chrome) bolts that would be installed plus the addition of a bore for the new dowel, I'm certain it would hold up to some pretty good power regardless of a missing bolt.
Second idea: A full adapter plate. This would have to thick enough to cover the dowels completely as well as include new dowels for the 2g trans. It would also need to be thick enough to supprt the entire tans. However, even at the bare minimum to cover the dowels and support the trans, I would be shifting the entire transmission over about 1/2". This means the passenger side axle would be an 1/2" too long and the driver side axle would be 1/2" too short. That would be acceptable, but I doubt the carrier bearing for the driver side axle would match up. So that would mean you now need a custom bracket for the carrier bearing. Then you have the issue of the transfer case on AWD cars since it bolts up to the transmission. The transfer case being shifted 1/2" could cause premature wear on the driveshaft. This could be solved by extending the adapter plate to fit the transfer case, but then your reudcing the surface area of the output shaft which could cause the splines to wear prematurely as well. Here's a rough sketch of what I'm talking about. The red is where the adapter plate would go, the blue is where it would need to be extended for AWD application. It would also need to extend to house the starter which isn't shown. Overall, this idea seems too complicated to be justified.
Third idea: Custom bell housing. F*** that. Moving on.
Fourth and best idea: A small triangle shaped peice of aluminum or steel that bolts to the engine side of the upper right hand trans bolt. It could have a dowel on it for alignment and then I could remove the dowel from the wrong spot. Or bore the trans bolt hole so there are 3 dowels supporting the trans! This would be cheap, very easy, and would give even the high HP guys a chance to use the 3g blocks. Here's a rough sketch of what I'm talking about
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This would truly be the most optimal way of doing this and will be the route I try to take first. It would let me keep the trans bolted straight to the engine, support the trans with all of the factory bolt locations, and I could use a very thick (around 1" or so at the corner) bracket for the missing bolt hole location.
Thoughts? Questions? Alternative ideas?