The 350 is the small block, and in 1986 it would be GM corporate blue.
probably a 350 small block
stock brand of tires for the 2000 chevy silverado 4x4 ext cab
All the speakers in a 1991 Chevy Silverado should be 4x6 if they are stock.
Yes they are interchangeable.
16x7
No, Chevy changed the wiring harness in 2003. and the way it is mounted, it can be made to work though.
285 hp
P245/75 R16 Chevy stock size
Should be the 700R4
it will probably be 3.73
Stock speakers should be 4x6's
Generally, a stock silverado will have four speakers; two in the dashboard and two behind the seat.