Since this category is 305-350, I'll have to assume that YOUR engine is one of the two mentioned.
The 1990 Chev 305 and 350 did not use a timing belt. They used a timing chain, and unless something really odd happened, you should never need to replace the timing chain until you rebuild the engine.
It does not have a timing belt. The cam is chaindriven.
There is no timing belt on a 305 unless it is an aftermarket belt drive system.
The 1990 has a chain. The 1991 has a belt.
Chain.
A 2000 Chevy S10 does not have a timing belt.
The 96 Chevy Blazer does not have a timing belt.
No Belt=It has a Timing Chain.=
chain
Doesn't have a timing belt.
Timing belt
The 97 Chevy Suburban doesn't have a timing belt.
it has a chain not a belt