I'm also a fan of Optima batteries. I've used them whenever funds could allow and they've always been complete tanks.

 

Jim I will say it's a tight fit...I know the optima 78 fits the best out of the 78 groups, but is pricey. Sometimes you can get lucky and get a reconditioned agm, that was just recharged improperly. This is mine..

 

O3jawja, that is scary that you say the group 78 is a tight fit because the 75 for me is a tight fit. I am always hoping for a battery with one of those lift handles, so you can drop it straight down onto the tray. Maybe I should just pay extra for the best no. 75 with the higher CCA and accept that battery. It is hard being 'cheap' in this world. O'Reilly's has a Group 75 with a strong 690 CCA. This is the O'Reilly Super Start Extreme. It's dimensions are 9.75 x 7.0 x 7.25, so it is a bigger battery than most 75's are in the 9.75 length.
The Super Start Extreme is $159.99 plus core charge. For Labor Day sale, they give you 25 % off.

 

Jim it isn't too bad. I have to really wiggle it in there, but all my terminals are at a safe distance. Jim I always wondered if we could relocate or change overflow tank what kind of room would we have for a battery?

 

I said in my post no. 13 above that :
The 'O'Reilly's' Super Start Extreme is $159.99 plus core charge. For Labor Day sale, they give you 25 % off.
Well, I found out that isn't true. O'Reilly's isn't offering the 25% off on batteries and for some strange reason will only ship batteries to your home. IOW no pick up at store free. Sorry, O'Reilly, but those are two deal busters for me.

I verified that on O'Reilly's 'chat'.

It is back to Walmart's supercenter to try for a Group 78 fitment into a small 'Group 75' battery tray. More CCA at the same price? It is worth a try. We'll see.

 

Jim let me pick your brain for bit. Do you think if someone completely gutted the jack area in the rear, that they could fit any extra battery back there. Maybe a 51 group or a taller telecom style battery like a northstar?

 

Yesterday, I did get a new Walmart EverStart Maxx battery in Group size 78 s for $93.76 and with fees, taxes, core charge, etc. it was a total of $102.32. That is a buy for a CCA of 650. Remember the recommended 75 is the same $93,76 and it only had 550 CCA. Did it fit ? Yes, but with some maneuvering and removing the fan shroud. The rad had to be moved so that the battery would clear the rad. cap. This is a two person job. My Walmart installer was cooperative, My plug in Volt meter shows a 12.6 VDC which is correct: 6 cells X 2.1 VDC per cell It has a 3 year 'replace free' warranty with an addition 2 years Pro Rated. It DID NOT come with a handle like the catalog picture showed. That would have been nice to have on this particular job. I think I read that this battery is made by Exide. I did see that Walmart also carries Oddessy batteries.
Just a note. Walmart wants to get into Online sales to compete with Amazon. Let me tell you , they have a long way to go.

 

Happy you got a good deal on the battery

 

O3jawja.I saw your question in post no. 16 above. Are you wanting to wire the second battery in parallel like the diesel guys do to have the same VDC but with more amps ? Or to have it as a 'back up battery' in event of a primary battery failure ? Either way, it is an interesting question, but I am afraid I can't help you. Maybe some one else here cab help. Please state how you are wanting to wire it up to provoke a response.

 

Jim..I would wire them in parallel, probably run 1/0 under the frame up to jack area. These are the moment I miss my 2008 sierra. I had so much room for an extra battery, terminal blocks, fuse panels, etc. I may include a relay or manual switch to disconnect batteries