Steves41,
I'm not 100% on this, but I believe the 216 carburetor had a 2- 11/16" bolt spacing and the 235 had a 2-15/16". These have SAE numbers associated with them although I don't know what they are.
I thought the 261 used the same bolt spacing as the 235! The difference between the two bolt spacings is only 1/4" isn't it.
Stuart
