SM creeper 1st gear install

I found a SM with the Code: M J

My book says this is a low speed 1st gear, if I want to put this in my other SM will I need to install the entire trans. or can I just install the 1st gear?

you will have to take top cover off and get into the transmission. Will have to remove top shaft and switch the gear....I dont think there is any need to split tractor...I would be making sure the teeth are the same pitch before you break into this..A GOOD Days work if not 2!

you will have to take top cover off and get into the transmission. Will have to remove top shaft and switch the gear....I dont think there is any need to split tractor...I would be making sure the teeth are the same pitch before you break into this..A GOOD Days work if not 2!

Cory is not even close. You cannot just change one spur gear. They come in sets and on a M the tooth total for each speed (1st thru 4th) has to add up to 73 teeth. (And don't worry about the gear pitch. If I remember corectly, all the gears are 5 pitch but it doesn't matter.)

That means the countershaft 1st gear has to be changed as well. However, the low-low countershaft gear is integral with the countershaft (that means one piece). Because the regular first gear is a cluster gear (1st and 2nd), you also need the low-low 2nd gear for the countershaft. The reverse idler gear also has to be changed.

The differential has to come out to liberate the mainshaft. The left side bull pinion has to come out as well as the bull pinion cage. Before you do that the bull gear has to disappear. When all that is done, remove the PTO and PTO extension shaft. You can now get to the countershaft. I may have missed a few steps so get a manual. I & T may be good enough.

If you want to save yourself all this trouble, just swap the complete rear frames with axle housings attached. Or change engines because I assume one of your engines is better than the other one. I suggest you go to caseih.com to verify that the low-low attachment includes 3 gears and a shaft. Good luck.