I have one in my 69 Camaro and I think I got it from Ground Up but it has been several years.
No I did not get the terminal extentions, and did not need them anyway.
My last battery was a 7 yr old AC Delco and it had a flat top. Last fall I went to replace it and the guy brings out the same # AC and now they have those stupid square caps
that won't allow the topper to fit.
I ended up with a battery from NAPA that has a flat top. The whole thing is a tight squeez in a Camaro but it does the job.
Mike