Where can i find a hole to run my amp wire?

Question

I have a 1990 gmc 1500

Answer 1

Check around the brake booster under your hood. If I'm not mistaken there is a grommet to run through, if not there is a large area where you can drill a hole where there could be a clutch cable (if its an auto). Just basically open your hood and look at and in all of the nooks and crannies on the firewall.......

Answer 2

In most cases there is plenty of room through the firewall with the other wiring harnesses. If that's where you need to run wire?  You can also drill your own but keep in mind you'll need to bush it with a grommet to avoid chafing.