Replace Ultegra 6600 STI lever I need to replace my Ultegra 6600 right hand shifter as the ratcheting system is gone. The rest of the groupset is all the same 6600 series.

I am having a hard time sourcing just a right hand side shifter and they cost more than I really want to spend.

I am having a hard time working out what shimano shifters are compatible.  I gather there has been a change in the brake pull length, so its critical that I get a compatible shifter for the 6600 brake.

Will a Tiagra 10 speed 5400 combined shifter/brake lever be compatible?

Is there a compatibility chart for the brake pull options?

Any suggestions appreciated.
The Ultegra 6600 STI lever is available as a right hand only part. It should cost around $400 dollars for the right shifter only, and around $600 dollars for the set.

Any Shimano 10 speed rear shifter, including the new Tiagra 4600 10 speed will be compatible. If you have current brakes, and you use a 10 speed STI lever, as previously noted, you will have no problem with the brake pull.

The compatibility chart can be found here.