In swapping the T-18A onto this Jeep project, a good tip was passed onto me from Mike of www.Jeepfan.com.  This tip has to do with the stock clutch fork being used in the stock bell housing of the Jeep.  When a T-18 is swapped onto the Jeep, the lower drivers side bolt that holds the bell housing to the transmission is replaced by a stud that is pressed through the bell housing.  This stud is also located directly behind the fork as pictured to the right and indicated by the white arrow.  It may not be apparent while assembling the bell housing  and transmission but when the clutch fork is fully engaged (compressed) there would be contact between this new stud in the bell housing and the clutch fork itself.  The result is a twisting of the fork and the throwout bearing which results in a binding of the throwout bearing and gradual wear of the input shaft and throwout bearing.

While I don't know for sure because this is a swapped and not a stock T-18, it's possible that the stock setup used a different clutch fork that may have resembled the stock fork that this T-18A had as pictured below.  However these forks were not interchangeable and a  stock Jeep fork was to be used.

Grinding out the side of the fork.

Notch around the stud.

Re-install Fork.

Test for contact using full range of motion.  Mark where additional contact is being made and remove more material if needed.

Additional information on this can be found
 www.Jeepfan.com.