i rewired the alt output on my truck, (it's a 77 but i had the '79 wiring diagram), the bulkhead was bad, the connection going into it and feeding the electronics inside and the ammeter had alot of resistance.
after rewiring, the turn signals did flash alot more consistent, also brighter and faster.
wipers also work alot better, even at idle...

i found this after i had rewired it, it's similar to what i did.
https://ramchargercentral.com/electrical/ammeter-bypassbulkhead-fix/