Aside from the tag....is there any difference between a 1971 W30 trans and a 1971 442 trans ?

Or are all TH400s in a given year (or across years) the same ?

 

Well, GM didn't typically give identical parts different designations...

Internal differences include the number of clutch plates in a given drum, the stall speed of the converter, the weights on the governor, the configuration of the valve body and spacer plate, the stiffness of various springs used in the spool valves and accumulators, etc.

 

thanks...at a minumum I figure they did just put different tags on the same transmission in different makes...e.g. there must have been a Buick trans identical to an Olds trans except for the tag.

 

If Hydramatic did put different tags on the same trans for different GM Divisions, it would've been pure coincidence. The Divisions really were quite independent back then. While all GM A-bodies shared many chassis components, each Division was responsible for fine-tuning their combinations: spring rates and heights, shocks, body mounts, and yes, transmission shift points and firmness.