I have 800CCA,  1000 CA.  Looking for the highest I can go.  Any recommendations.  Highest Duralast now is only 750CCA.

Basically only 3 major battery manufactures. Johnson Control, Exide and Deka/East Penn.  While I do have to be a bit bias as I work for an Interstate Battery distributor, Costco batteries are now labeled Interstate instead of Kirkland(Costco's label).  In fact, the batteries are the same batteries, just the label has changed... and as far as I know they do have the best prices, and most of their batteries are equivalent to our  Megatron Plus line(basically the heaviest battery line we have). Going through the core returns we get from Costco, it looks like their sale price is actually lower than our wholesale cost on most of the batteries they carry. 

As for recommendation for your car, it kinda depends on what part of the country you hail from. If you are in a colder climate area (Minnesota for example) you would want the heaviest cold crank amps you can get. But if you store your car for the winter that would probably not be an issue.  Around my parts(Tennessee) we tend to see the middle of the road cranking amps batteries have a better life span.  Seeing you are in Louisiana, especially if in the southern area where temps don't get all that cold, I personally would say a MT-78 should do if you still have the side post set up. If by chance you converted to a top post battery, then a group 34 (MT-34 interstate part number or even a C78DT-XHD which is a dual post(top and side post) or MT-78DT.  Personally I do like the MT-34 or C78DT although the C78DT does have a shorter Warranty life....

That's true to a point Gunslinger...  but when you consider a JCI is pumping out over 135 million batteries a year, it would seem a bit illogical to have multi-multi spec batteries.  While there is 3-4 different variants of one particular size of a battery, it stands to reason that JCI couldn't make production quota's if each customer had a particular spec.  For the most part, Wal-mart, Costco, and others buy their batteries in lieu of warranties from JCI.  Interstate doesn't.  That kinda gives us a bit of an edge as far as warranties for customers. Wal-Mart, Advance,Autozone, and others tend to have shorter warranty periods and that gives them a little bit of an edge for pricing to their customers.  Basically with an Interstate battery you are paying for a little better warranty as compared to most others outlets and a Green or Black and white case instead of the all black case(which does add to the overall cost to our batteries... 

As for varying the specifications for a battery, it really boils down to the number of plates per cell. The more plates the more cranking amps.  So if Wal-mart has a battery rated at 500 CCA(cold crank amps), then there has to be a certain number of plates to obtain that particular rating. Well, if Interstate has the same group size battery with a rating of 500 CCA, then it too would (or should) have the same number of plates.. a lot of times the battery rating on the label is often under-rated so that the customer gets their spec, but the plant doesn't have to change their process just for that one customer...

I've noticed this past year that some of our batteries are starting to go to the all black case without the Interstate name imbossed on the case. Instead they just have the name Interstate on a label. This is happening on our odd-ball sized batteries, ones that do not have much of a market to make it viable to have the molded case with the Interstate name and colors. 

Oh since I mentioned plate numbers within a battery, kinda like putting rocks in a glass of water, the more plates or rocks, the less acid or water(in the case of the glass).... while most of our vetts the battery is behind the seat so engine compartment heat is not much of an issue, but if it was under the hood, as we all know, heat kills.  No different with a battery.  The acid solution does help 'cool' the battery. So high crank batteries do not fair well in the deep south and west. up north and beyond are more suited for the '1000' cold crank batteries.. Granted this is not an absolute, but it does trend this way more often than not... 

hope this helps and enlightens someone... given my typing skills are severly taxed ;)