that is the rod that allows you to drop a gear when you are wanting to pass someone on the interstate. I always called it the kickdown cable/linkage. I was able to find an appropriate hole on my carburetor throttle bracketand I put a bolt through it and double nutted (jammed the nuts together) to allow slop in the bolt for the linkage to pivot from the throttle linkage.
Once you have it hooked up, you can road test your drop down gear ability by stepping on the skinny cable. I had it where if I was cruising at 25mph in 3rd gear it would drop all the way down into 1st. Mostly it came in handy on the interstate when passing somebody.. but 3rd gear for me was turning 2600 rpm’s at 70 so I was already making good power at those speeds.
I recently swapped my fmx (crappyer version of c6) out for a Borg Warner T5 out of a 94 mustang. I got an old cast iron bell housing from eBay, a new billet flywheel, and went with a mechanical clutch linkage. I love it. I can really drive it now… shifting gears and making more power!
Best of luck!
