Shifters:
http://www.nashbar.com/bikes/Product...08_-1___202436
Plus cassette, chain, brakes pads, tires/tubes, and RD jockey wheels.
You intend this as a rain bike...why on earth throw $800 at it? I'd cap the investment around $375 - otherwise sell it and demote the 5900 as others have suggested.
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"The older you do get, the more rules they're gonna try to get you to follow. You just gotta keep livin', man, L-I-V-I-N." - Wooderson
'14 carbon Synapse - '12 CAAD 10 5 - '99 Gary Fisher Big Sur