[SOLVED]
It was bad alternator, used a bulb between D+ and battery positive to know, with old alternator it lit up.

Its my first post, sorry if in wrong category.

Alternator doesn't charge and dashboard battery light doesn't light up, 12V from battery when shutdown and 11.5V or less when running.

I have tried:
new bulb and socket,
old alternator,
removing subwoofer cables,
new wires and plug to alternator (B+ spades directly to battery positive, D+ to dashboard warning light plus),

I'm going to try if making extra ground wire would help but don't believe it would.

Battery and alternator are just 2 months old, I barely understand electricity so please go easy on me haha. It's 1987 sedan Sierra 2.0 OHC (DFTH carb) if it anyhow depends. Thanks in advance! Really need it running asap.