OK, I have two Turbonetics turbos for my BBC 68 Camaro. I bought two 4 bolt T04 discharge flanges off Ebay and the bolt holes don't line up.
The turbo has 4 3/16' distance center to center bolt holes and the flange is 4". How many different bolt hole patterns are there for a T04 on center discharge flange? I am looking for a decent price for a flange in mild steel for a 3" pipe. Will I be forced to buy the flanges from Turbonetics?

 

My mistake, the post below was complaining about strange, non-standard inlet flanges. The discharge flange you have sounds like it's the ~4" bolt circle diameter flange often found on Garrett GTs with T3 inlet flanges.

Now, the rant on weird T4 inlet flanges...

There's at least two things known as T4 flanges out there for the inlet. For some perverse reason, Garrett advertises their GT40 turbos as all having a T4 flange, but the GT4082 and GT4088 have different bolt patterns. You'd expect somebody like SS Autochrome to pull that off, but Garrett?

Their catalog shows a flange with a 3.5" x 2.75" bolt pattern - for both of those "T4" turbos, even though the two of them don't quite match up. Found this out the hard way on my Dart.