Who used common battery instead of long "Jag" battery?
 

I remember buying some "short" battery from junk yard for $20, it worked fine.

You pays your money and you takes your chance. :icon_wink:

If you have thoughts of going "cheap" on the battery front, these cars are NOT where you want to be doing it.

So many electrical problems (real as well as spurious) are attributed to failing batteries in these cars that it is simply not worth the monetary savings to scrimp on lousy batteries. Put a decent battery in the car, take care of it, and your overall ownership experience will be so much better....

My 97 had a basic battery when I bought it and I ran it hat way for several months. As long as you use a maintainer to keep it charged it will be fine. But I don't think the difference in cost is that significant.

Ditto the comments above. I recommend an Absorbed Glass Mat (AGM) new battery and a C-TEK battery tender to keep it up to speed. (I have one in my '99 XK8 and it has kept my electrical system free of "bugs.")
Don't go cheap when it comes to the electrical system on our cars.

When I purchased my '99 years ago it had a Walmart battery that had bushings on the hold down rods as it was small in length and height. It lasted for awhile but I put the correct battery in when it failed. Why try and save a few dollars on an incorrect battery when it is so vital to the car? Save somewhere else.

I have a battery tester, paid $50 20 years ago. I can check any battery (except cellphone battery :)), no problem. You can go Autozone or Advanceauto, they can check battery w/o removing it.

More you know less you pay...:D