I am rebuilding an NRH3 5 speed tranny for the first time. I have the countershaft reassembled with synchrotech carbon Synchros. There is a brass synchro in the package that is identified as the reverse synchro for the main shaft. Which synchro position do I use this synchro for? I've read through the diy transmission thread but still unclear where this "reverse synchro" sits on the main shaft.