Can anyone advise the engine code letters for the 66 427 390 HP engine ???

One source I have indicates II, IH & IJ for full size Chevy and IM, IL for the Vette.

Hope this helps.

Thanks Don .. I should have mentioned 4spd not sure if chevrolet or corvette non calif car

pass car 4speed-IH or II auto-IJ or IO corvette 4speed-IL or IM auto-IQ or IR Hard to find block dont see many around anymore thanx to the drag racers of the 60's and 70's.

Thanks alot for info .... it really helps