classic motorcycle forum

The DT was last listed in the 1933 catalog with no image. The Rudge site lists the catalogs.
Victor Martin was the only dealer of JAP engines from the factory. The Comerford predates the Martin frame- Rudge copy

The Crocker frame was built around the Indian engine. This same frame was used for the 1934 OHV single.
The Rudge frame was never used. That would take 2 bikes to make 1. The Rudge DT was last listed in 1933 catalog. The JAP was the king of the track.

This bike has Indian on the tank not Crocker, because it's a Crocker frame but Indian engine.

1936 LA yellow pages. George Beerup and Fred Schunk. Both of these buildings are still standing today. Can be seen on google maps. Beerup shop is now a "Green Cross"

A 'Rudge-Crocker' would be a Rudge frame and a Crocker engine combination = never existed.
A search on the net will show 'Rudge-Crocker' examples at the auction houses, which is where and why they exist. MONEY!

The design of the Crocker is certainly based on British engines. It made sense to take a close look at Brit bikes.   
Charles Franklin designs were based on British bikes. He died in 1932 and Indian had no one to design anything.

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February 1970, Cycle-Sport mag, by Geroge Hays