IDK about that. I never heard of that. What I heard .....LOL..... was the 400 was brought out to replace the 383 and the 360 was brought out to replace the 340.
Anyways, let's not forget about the 400HP engines with the higher lift camshaft that was rated between 245-255 ponies depending on the year and application.
Considering the engine output in the way it was measured, I think with the old method, the numbers would have been very comparable to the 383. With both engines, ( 360 - 400 ) The Government emissions standards killed the rated HP. Between the two, Gov. reg's and new way of testing HP, these engines got a bad rap. "It's a P.O.S. smog motor. Worthless."
