I don't spend a lot of time in the Brake Forum, and I have done some searches, but I'll just cut to the chase: What is the least-expensive Big Brake Kit you can get for the Tundra?
How do I tell if I have the smaller calipers?If you still have the smaller calipers the best thing to do is simply upgrade to the larger ones. http://www.tundrasolutions.com/forums/brakes/65633-upgrade-your-early-tundra-brakes-1-a/
There are some larger brake kit made by the aftermarket but most require a wheel change and they are basically racing brakes which seem to last forever on the street but can be extremely expensive to maintain.
Well, I definately have the old calipers....Look in the TSB section for this TSB
BR001-03 FRONT BRAKE COMPONENT IDENTIFICATION (REVISED)
There is a picture of both the old and new calipers side by side. You should be able to tell which you have after comparing your calipers to the ones in the pictures.