There's a very short demo of the yellow Dirt Searcher on YT, which the poster identifies as a Model 1354A from 1971.
I've noticed that Hoover Ltd. produced the same model number in different color schemes; often for exclusive store models, but possibly also for other sales lines or for exports. The varied colors may also indicate production of the same model at foreign factories. Further, a different letter suffix on the model number seems to indicate production at a foreign factory.