I was told that for that transmission to operate correctly, there is some linkage related to the carburetor that requires skilled adjustment. Is that correct?
That is correct. I had a 57 Pontiac that came with a Roto Hydromatic. I replaced that with a dual-range B&M copy out of a 55 Pontiac that a local guy modified. I couldn't get the carburetor linkage off the 55 in the bone yard as someone had beat me to it. So I attempted to fabricate something that would work. It never shifted right and the abrupt shifts would chirp the cheater slicks and the U-joints lasted only weeks.
55 was the last year for the dual-range hydomatic on Pontiacs. I have believed that was true across the GM line including Olds and Cad. I don't know when Buick abandoned the DynaFlow. The Roto was used until the turbo hydromatic came along in 63 or so. I also had a 62 Olds with a Roto Hydromatic.
Anyhow don't scrap the dual-range. It'll be worth a lot to somebody.
