I have a show car, a 1992 GMC Typhoon ( 120,000 miles) that I just replaced the battery after 6 years. This car is on a battery tender 100 % of the time.
The battery was a Auto Zone Duralast and that is what I replaced it with yesterday.
Is there a battery out there that will last longer ?

Cb

 

6 year life is not bad for your situation. Storing a battery inside will make it last longer.

 

While 6 years is not a bad life cycle for a Lead-Acid Auto Battery, there are options to extend the life of your starting battery;

1) Absorbed Glass Matt (AGM) Lead-Acid Battery. I usually get 7+ years out of these on my cars. I use a Tender and keep the battery in a good charge condition.
2) Lithium-ion Battery. This is new(er) technology and claimed to last 10 years. Antigravity Batteries makes a line of Automotive starter batteries you might consider.

 

Last 3 batteries I bought via NAPA Online. I was able to find a coupon, order online then drive by my local store for a pick up. They sell both traditional and AGMs with prices ranging from $100 to $350. I'm not sure if its worth spending 2X the money just to get one more year out of your battery so I'd say the best value is their Duralast produce line. Moving to a Lithium Ion battery is 4X the price to get 2X the durability so I don't think those products are mature enough, besides the benefit here is the weight savings which is't a premium for your car.