Being that the 235 engine ended in 1962 in the USA, when did the switch from a cast iron powerglide to an aluminum powerglide take place ?

Did any 235's use an aluminum powerglide ?

The first aluminum Power Glide was used in the 1960 Corvair.
Next it was used in the 1962 Chevy II and full sized cars with 327 engines.
In 1963 it was used in all Chevrolets and the only automatic trans. used until the Turbohydramatic 400 came in mid year for the 396 engine.
It was never used with a 235 engine. The new 230 cubic engine and aluminum P.G. reduced car weight by almost 300 pounds.

Turboglide was available from 1957-1961 for basic 283 and 348 engines and also had an aluminum case. Some of its features such as a multipule clutch pac rather than a reverse band were used in the aluminum P.G.
The last aluminum P.G. for a full sized car was 1970 with Turbohydramatic 350 being available along with P.G available for base engines in 1969 and 1970.

Gene, were the 235 cast iron PowerGlides the same or different from the pre 1962 V8 PowerGlides ?

Was there a DIFFERENT spacer or adapter on the bell housing for a 235 cast iron powerglide , as opposed to the 283 cast iron powerglide spacer or adapter ??

All iron P.G's used an adaptor between the main case and engine. The adaptor was sold with the case at a matched unit.
The adaptor was not used with any of the alauminum case units as they bolted directly to the engine. On cars with the aluminum case transmissions the starter bolted up in a different manner and the rear starter housing could be changed to adapt.
The six and eight Cyl. adaptors were different.

When you speak of an "adapter" for the iron PowerGlide, are you speaking of the DETACHED bell housing, used on the iron PowerGlide ?

Yes.....

OK Gene, thanks ..... all clear in my head, for now !

It would be nice if that adapter for the cast iron P/G would work with the aluminum version trans.

The bell for the aluminum tranny is part of the case, where the bell or adapter for the cast iron is a separate piece.