When upgrading my Klein I ran into an interesting and fairly unique problem. It had an odd pair of shifter bosses (which I have since found out are called "aero shifter bosses") that were brazed onto the top of the downtube, rather then on the sides of the downtube. For downtube shifters (the usual style of shifter used when the bicycle was made) this isn't a problem, but these shifter bosses wouldn't work with the cable stops required to use barend or STI shifters. To work around this my local Klein dealer ordered a kit from Klein that added a new pair of shifter bosses. Installing them required drilling two 1/4" holes through the frame where the bosses were to be installed.
The new bosses work great, although it does look a bit funny to have the old boss still mounted there. Klein offered to remove it and repaint the frame, but the cost was going to be over $300.