Looking for help on which main shaft to use. They are both type r but i noticed one has a bigger oil passage than the other. Any help would be appreciated. Thanks

 

Use the one with the oil guide insert (smaller oil passage). The other ITR mainshaft with the insert removed shoud not be reused. The plastic oil guide plate in the top case feeds into this passage and will not have proper lubrication without the insert.

 

I figured that would be the answer. thanks for the quick response and the deal on the rebuild kit i just got from you