904 and small block

[ir3333]

..is there a preferred year to use or any year to avoid?
wanting a 904 to use with a cast crank 340.i have the flexplate with the small bite out of it and will run a neutral balance torque converter.

 

[fishy68]

I'm not a 904 guru but everything I've read points to 72 or newer being what to use. You probably don't want a 67 or older as they were the smaller input shaft with 18 splines and the converter had the small register that was only for 67 and older engines. They can still be used if an adaptor is bought to adapt the converter to a 68 or newer engine but converter selection is much less than 68 and up and may cost more. I believe 77 was the start of lockup 904's so you'll probably want to avoid them also. You can identify them by the input shaft having 26 splines vs. 27 for a non-lockup and the end of the input shaft is machined down smooth for about 1/2"