So skorchmp ,
your sayin that a Group 34 will fit, even clear the hood underside channel on the Pass side of it?
i.e. The battery post does not touch the underside of the hood ?
Am thinking of upgrading my batt (it's very dead now) in 92 XJ
but am concerned about hood clearance to Neg Post on battery.

Not sure what kind if battery I have but it's super beast. Can run the radio loud for 3 hours without a flinch.

Yep, a Group 34 fits perfectly under the hood of my '90 XJ. The 1998-2001 XJ's had Group 34 batteries as stock, for whatever that's worth. I'm not sure how much clearance there is, but as long as the positive terminal is towards the engine, with the negative terminal towards the fender, all is well. Look at all the A/C gear on the top of the engine, all those lines clear the hood, and the positive terminal of the Group 34 is below the level of some of that stuff on top. The negative terminal doesn't touch the hood either, as far as I can tell. I'm gonna get some play-doh, and put ***** of it on the terminals at some point just out of curiosity, to measure clearance. FWIW, I love having the bigger battery, when I crank in the cold, the difference is immediately apparent.

Will try the fit. I need the super cold cranking power as well here in Colorado.

Just picked up the Interstate Mega Tron MT-34 from Summit Racing here in Sparks NV, $101 plus tax.
Slipped right in, perfect fit.
Thank you posters for the right advice!

http://starparts.chrysler.com/starlibrary/00bat25.pdf & scroll down to Jeep section.

Please look at post dates. This thread was 2 years old when it was replied to 3 years ago.

Duralast 34-DLG has been excellent for me. Zero issues even sitting in -15*f weather for a week.
Always cranks hard, and handled my audio system without any complaints.
Plus it's super easy to get a replacement at any Autozone.

Old threads never die, lol. Google searches aren't date friendly (well, much).

I came here Oct '17 ...needing to know some battery facts for my 21 year old XJ. And share.

...my 8 yr 1 mo old, lately much abused Wally World 58-3J battery (I was too lazy to smog and license it because it was throwing a P0443 code, but we have guests coming in soon so I have to fix it today ...and a cell has obviously died due to my maintenance negligence), and I wanted to see what The Clan knew about suitable replacements.

Knowledge never dies.

...and I discovered a series 34 should fit fine, so I'm going to upgrade from 540 CCA to 800 CCA (which one bloke said was quite suitable for the 6 banger, and another discussed fitment).

So you future readers/commenters, take no heed to age. Pass on your some day current knowledge to those that come after.

...blessings on all in the past who helped me today. Cheers, honorable ancestors.

I just put a new battery in my 89 today. The old Costco battery (5 years plus) seemed to work fine but wouldn't keep the charge over 12v even after fully charging with a charger. I figured it was time for a charnge . As the old battery came with a 100 month warranty, I took it back to Costco and got a 40% rebate which I used to offset the cost a new Costco battery. Bit of an issue though: the old battery was a Costco #1 which they don't seem to offer any more. I wasn't aware of the series 34 thing so I went for a slightly larger battery (Costco #6 @ $99 CDN) knowing it would be a tight fit but it offered 1000 CCA! I had to cut the lip off the inboard side of the battery tray to get the battery to fit (tray is held to lower fender with three studs/nuts). The base of the new battery fits snugly in the tray 'front to back', but hangs out about 1/2 inch over the newly opened inboard tray end. Nothing rubbing (although the upper rad hose is pretty crowded - I'm going to come up with some sort of a shield to minimize chafing of the hose).

Another minor problem: even though the battery fits 'front to back' in the tray, the 'front to back' top clamp was not wide enough to accommodate the new battery. I got around this by cutting the back lip off the clamp so that part of the clamp is only pushing down on the top of the battery, not the side. Added a strip of foam to the clamp to provide some cushion. Because the battery is not centred in the tray, the top clamp is close, but not touching, the outboard fill cap cover - so long as the battery stays put. I'll watch/tighten things over the next few days to ensure the battery is not roaming around the engine compartment.