What size battery are you guys using-group 27 or 34? Going to replace the battery in my 63 Starfire and want to be as correct as possible to make it fit properly in the tray along with the hold down parts. Car current has a group 34 and does not seem to fit properly. Thank you.

 

I can't remember for sure what 63 uses but 64 uses a Group 60K which is currently available only as a reproduction battery.

There are a couple of Asian car batteries that are close in size to the 60K. I think Group 51 or 53. Ford style 29NF are close too.

Picture of the battery tray and mounting and I can give a better answer. I can't remember if 63 puts it in front of core support like 64 or crossways of the core support like 62.

 

The group 60K battery was used in '63 's .
As mentioned there other batteries that " kind of fit "
But if you want one that fits right , then you will have to pay antique battery prices
.Delco 60K AGM Classic Car Sealed Scrip Battery (batterycentralmall.com)

 

I think Group 27 is about as close as you can get.. 12 1/16, 6 13/16, 8 7/8 vs Group 60 13 1/16, 6 5/16, 8 7/8. Thanks.

 

Here are the charts you need including a conversion chat to a newer style.

 

Thank you.