We have several 9670sts pulling 612c's however non are chopping , if you have a chopping head be ready for some real nightmares, low power, electric clutch failures, drive shaft hanger bearing failures, and feederhouse drive line failures, since the hi torque drive is 12 row ready[picking] not chopping, if you have a chopping head your dealer should have put you in to a 9770sts with commandtouch feederhouse drive, then you at least be able to pick and chop. good luck.