I have changed out about 6 of them. If you need a hand or get stuck give me a call. Kevin, 509-209-1021. Always willing to help out a fellow sledder.
You have to start by removing the speedo setup on the clutch side. Remove all the bolts. Remember their order, some are longer than others. Remove the bearing mount completely but be siure to support the drive shaft so you do not damage your gear case on the other side by dropping it to low on the clutch side. There are 2 small bolts on the drive shaft that hold the bearing housing in place, don't forget to put them back tight when you put it back together.
Next you have to pull your brake assembly apart. Remove the emergency brake then remove the 2 bolts that hold the brake rotor in place. DON'T remove the brake line or you will have to bleed it and reset it. Then remove the drain plug from the bottom of the chain case. Get all the oil out. Then remove all the chain case bolts. Pull the cover off slowly and don't use a flat head to pry it off. Once you get the cover off you will see all the gearing. There is one bolt on the reverse gear assembly that that goes into the drive shaft. That has to be taken out. Place everything on a table as you take it out of the gear box so you don't miss anything. Be careful, there is a tiny spring in that reverse gear assembly that you cannot lose. I start remving the gear case assembly by taking out the tensioner first, this way you get slack in the chain to work with but the chain probably won't come off unless you take the 2 gear assemblys out at the same time you remove the chain. Have a buddy help you so you don't drop anything.
Once the chain case is apart and remove the circlip from the frame you can remove the drive shaft from the track. Reassemble when ready. If yours has reverse you must get rge reverse linkage lined up perfect to get the chain case on and for the reverse gear to engage. You WILL need someone to manipulate the linkage while someone pushes the cain case cover on. This make take a few tries to get it on. Make sure you tie your speedo lines back up to the frame when you are done.