If you run a shift kit, not all the check balls will be reinstalled. You'll need a clutch spring compressor to redo the seals on the internals and be very cautious upon putting the seals in place. The lip seals will definitey try your patience if you've not done a tranny as of yet. Check the wear on all thrust washers and replace if necessary. And the clutches will like life better if assembled a tad on the loose side. Not a lot loose and be sure to use your feeler gauges to check the clearances to make sure you are on spec according to the instructions I hope you're going to be using.