I know my sled is a 116" track as it sits, I'm not sure if the early 80's are the same...might be shorter but I don't know for sure. If they are like 100-108" you'll probly want to find a 121" skid instead of making rail extensions. I'm only making rail extensions because it's only an extra 5".
I won't be swapping out the shaft, just changing the drivers. Still waiting for the guy to get back to me. But I will definitely be taking pictures of build and updating as I go! If anybody has any ideas, they are welcome here!
You will love the ride and comfort of a 121" on these little sleds, makes a big difference IMO