So, I have my Titleist fitting for the T-series irons at the end of the month.  I am open minded to the fitting, but I was wondering something.  
If I get fit into a stock shaft offered by Titleist, great.  However, if I don't, is it possible to get my current shaft?  On the site, there is only one selection of the UST Mamiya Dart shaft (65g), that can be special ordered.  But can I put in a special request thru the fitter to get MY version of the shaft, which is either the 95g or 105g version of the Dart.  If not, if I buy the shafts, can I send them to Titleist to have the heads I want assembled?  Or if not, can the heads be sent to me so I can do the assembly?  What I don't want to have to do is remove the shafts that I'm "fitted" into, so I can put in MY current shaft.  It just delays the time it takes for me to get them on the course.  ;)  
I understand that there is a 'vetting' process that Titleist goes through in order to select the shafts that they feel are good enough to be offered.  However, what I don't understand is, why only a certain weight class would be offered & not others.  Darts are offered on the site Only in the 65g lightweight shaft, but are offered in so many other weight classes.  
Tell me something good Titleist!