I think it varies between the two depending on what options you have.
Airconditioning 68 340 and 318 I'm pretty confident all get the Federal. From the original poster's picture, it look like the lower pulley set is from an A/C car. So if his car was A/C I bet it had Federal pump originally. My 68 318 Dart with A/C had a federal pump. Until I ditched it for a Saginaw pump.
The non a/c cars usually depend on the gear ratio.
I've seen an unrestored green 68 340 notchback with a Saginaw in a magazine. You'd have to find original cars.
My 68 340 auto 3.23 sure grip had a saginaw pump. I is a std bore motor and was never rebuilt. BUT, I'm pretty sure the motor has been out and it has a replacement left side exhaust. Not an unrestored car.
BTW, the saginaw is a much better pump between the two. For longevity and operation.
