Hi all,
Owner of an old Murray mountain bike from mid 80’s.
Long story short. Purchased 4 months ago from an older couple who never used it and stored it indoors - 40$. Have 600 miles on it since mid August. Been flawless. New tires and pedals. That’s it. Heavy as crap but been super fun to ride.

One arm on the crank finally bit the dust. Not sure where to look for a replacement. I myself am unsure if bearing size is consistent on mountain bikes and all that stuff.

any help?