2003 Klein Attitude comp bottom bracket change type I have a 2003 Klein Attitude Comp, and I want to put a crankset I have on it.  However, the crankset is square taper and the current bb is not.  Does anyone know what size square taper bb can go in this model, if at all?

I found this picture on google search.  Note that the 2003 model is candy apple red.
I googled a few pics of the frame - looks like it has a standard 'English' threaded bottom bracket shell - 1.375" x 24 tpi. Cartridge square taper BBs are readily available for this shell.

You'll need to measure the width of the shell, it should be 68 or 73mm. You'll need a BB unit compatible with that width.

The tricky part is figuring out what axle length you need to get the chainline right for your bike with the crank you have. I don't have any direct experience for that but there are at least a few questions and answers on this site on that topic.

You'll also need to check the square taper type of the crank. I think the JIS type is the most common. More info here.