Just for clarification, there are folks who believe "South Pacific" was filmed under the same conditions as "Oklahoma!" re: Magna producing.
Magna produced "Oklahoma!" RKO distributed the Magna Todd-AO production and 20th Century-Fox distributed (and did nothing more on the film) the...
I totally did NOT have this experience. The Todd-AO "Oklahoma!" was absolutely wonderful. Nothing sounds dubbed. It's one of the best-sounding musicals in my collection.
The laserdisc of "Oklahoma!" featured a transfer of the Todd-AO version and it was superb! The DVD release with both 'Scope and Todd-AO versions was an unmitigated DISASTER!