great truck with 290hp and 410tq at 3200 rpms
I own a 93 Chevy Silverado K1500 4x4 with V8 350 TBI 5.7L. so unless Chevy has changed their blocks, i would suggest that naturally your block is a SB 350. However, since your question was about horsepower, not which block you have, I will tell you the horsepower. The 1998 Vortec 5.7 liter makes 255 horsepower.
315 hp
5.7 vortec
Vortec V-6
245 hp.
295 horsepower
About 290 hp.
285.
i belive its 160 or 180 if its a vortec
305 horsepower
270
What transmission does a 1998 Chevy silverado 4x4 with vortec 350 in it have...it has a 4L60E OR 4L80E...60 HAS 17 BOATS AND 80 HAS 18