is the battery for a 57- 58 olds available any where I think battery mall is defunct.

 

I found this one.
Don't know anything about them though.
Oldsmobile Antique Auto Battery (1954-1965) S60KL - BCM (batterycentralmall.com)

 

I have been looking at that same one for my '55. Its a Group 60. Nothing else allows the hold down to completely seat. I am running a Group 43, its a little too wide, so the hold down doesn't quit fit, but does hold the battery in place.

https://www.jegs.com/Sizecharts/bcigroup.html