Parts are not cheap at all but it's also brand new. Most people will find all they need at the junk yard on a well maintained mustang and grab everything for 500$ but the vast majority is that most trans are beat up and require a rebuilt to last .
Unlike the tr3650 that pretty much drop in as is with little modification on the cross member, the t56,t6060 needs more room around the trans tunnel and the mount is so out of the way that the cross member need to be heavily modified wich I personally do not like. On a stock 4.6 2v I dont see the need of a 6th gear unless you want to brag about but you guys with the 4.6 32V have a better power band to use of all of the gears but cost and modification becomes a factor.
Tr3650 uses a different yoke (31spline) but the stock drive shaft has the right lenght, only the t-45 needs a drive shaft spacer.