Will a 2003 trailblazer transmission fit in 1998 Chevy truck 4l60e the truck?

No, a 2003 Trailblazer transmission will not fit a 1998 Chevy truck with a 4L60E transmission. While both might be 4L60E transmissions, there are significant internal and external differences between the transmissions used in those vehicles over that time span. The bellhousing, which connects the transmission to the engine, will almost certainly be different, preventing it from bolting up. Even if the bellhousing *were* compatible, there are likely differences in the internal components, valve bodies, and computer controls that would make the installation problematic and unreliable. You would need a 4L60E transmission specifically designed for a 1998 Chevy truck.