Inliners International Forums General Discussion Engines Is a 235 & 261 harmonic balancer the same

The most important factors determining damper design are the crankshaft and main bearing data.
The 1954-* 235 and 261 engines use the same crankshaft and main bearing layout.
This is why the Gen-3 292 damper is not as close a match as frequently believed (following that favorite rule "if it fits, it must work"): the stroke length, crankshaft length, rod and main journal sizes, crank throw design, and main bearing layout are all very different.

GM does not spend R&R money to invent new parts unless needed, which is why the SBC engines use many different dampers.