You are going to ulduar lose all the block gear (IE your trinket, shield etc)
Shield there are a number of badge and the crafted titansteel all of which offer better stats and the block trinket you can replace with a dodge (first war medal etc) or another stam trinket (essence of gossomer)
The stuff hits dam hard blocking 2K off a hit isn't going to mean much when hits are around 12-15K in 10 man. You really dont care about block at all the diff between block a boss hit and getting white hit isnt enuf to worry about.
You need to punch you EH (stam and armor) as much as you can and push your pure avoidance dodge/parry as far as you can.
Next review your talents and glyphs there is no real trash tanking in ulduar the MT and OT need to be almost interchangable so you need to think about things like glyph of consecration and the 5 pts you have in benediction. A place to start for your talent builds and glyphs are
View topic - 3.2 Specs: Summary of options - Maintankadin
View topic - Theck's MATLAB TPS analysis (A Jonesy derivative work) - Maintankadin
Do that and you should cruise thru it will just be a matter of learning the fights.
** Remember Warcraft players fail in directions you never thought possible.