Nazareth is my all-time favorite band, in my opinion the heaviest and best record of all time is their Hair of the Dog - the original European version that doesn’t include Love Hurts (great song and performance, but it doesn’t belong on this record). I have listened to it since it was released 1975 and I never tire of it!
As I write this, I am listening to Opeth's new record (on cassette, actually, as I just got an awesome Nakamichi deck in the rack) ’The Last Will and Testament’ - it’s great and Opeth is a band I highly recommend exploring.
I’ve been collecting obscure records for more more than 30 years (which nowadays are easy to find and listen to on the web) and there’s a lot to discover, if you haven’t. For example, Night Sun - Mournin’, Hairy Sea - Can’t Get Through, Mistreater - Hell’s Fire, and Ocean - God’s Clown are examples of fantastic heavy albums!
In the mid 70s there were a lot of great American that released great music: for example Moxy, Starz, Angel, and Legs Diamond.
Man, there’s so much...