I’m using the clutch cylinder for the S10; sometimes the clutch will slip when I pop the clutch. My question is should I modify a clutch cylinder that is for the 6 speed or is the clutch cylinder for the original s10 ok. Could someone answer this question thanks. I am going to replace the clutch and would like to know before I change it.

 

Sounds like you have a bad clutch disc or pressure plate. The slave will not cause slippage like you describe. When swapping the LS1 w/T56, use all of the OEM LS1 clutch hydraulics. I wouldn't mix & match.