To fitting a Red Top Optima in a LS400 there are some thing that must be altered:

First you must make two 1/4 thick by 6 1/2 X 10" plastic shims ( plates ) to place under battery to raise it so the stock tie-down bracket will hold battery.

 

Then you must trim off bottom of battery box about 5/8"...........with tin snips

 

Then install the two plates in battery tray and new battery on top of them ,then the box over new battery ,install the top hold-down bracket and straighten out the 90degress bends on the battery cables to reinstall like picture.

 

The battery is a Optima Red Top number 34/78.............it has 800 CCA and 980 CA .....Best of all a 3 Year Free Replacement Not Pro Rated ! !

Also I was able to install the stock battery air cover without any alterations to it.

 

Nice write up........

What made you go w/ the red top......... I notice alot of folks like the yellow? Over here they still have the orange one and that was the one recommend for my car.

Im asking cause I been wanting the yellow.

 

The Red Top is a start battery with 800 CCA the stock battery is only about 500CCA and with the Hot weather in California you need a good battery.
Plus I do not play the Stereo when the car is off so the Red Top is the best for me.
It turns the starter so much faster it will extend the starter motors life.

 

Oh okay I see........

I want to have a nice stereo system in the future so the yellow will be best for me.

Again looks great

 

I have yellow top that is the same size and it drops in without any mods.

 

Cool makes it even easier.........

 

yes, its back from the dead - I had some trouble w/ the optima red 34/78 install on a 99 LS400, thought I'd share.

First, when I bought the battery, I found out it comes with a spacer. Battery + spacer is slightly (1/4") taller than the stock battery. The battery tie down fits perfectly, no modification required. (first pic)

Second, I was expecting to just attach the positive terminal - I could not. A 5min job turned into a 1hr mcguiver episode. The cable was not long enough. I had to extend the terminal. I used an aluminium strip L/W/Thick ~2"x5/8"x1/16". Then had to hack the positive terminal cover to fit. I also used some electrical tape to wrap the portion of the terminal that stuck out the back of the terminal cover. (second pic) The negative terminal fit perfectly.

 

you could also not put anything under it, use a 1x1x4 piece of plastic/wood under the tie down, and the cables fit fine.

il have some pics soon of the setup in my dad's '00 LS.

 

I just used a bit of brute force to get the positive terminal connected in my '98 LS (yellow top). Maybe not the best route, but my old battery was dead, so I needed something right away.