Posted: Jan 27, 2020
1969 Mustang Battery Size
Newer cars, including the Ford Mustang, typically have one option when it comes to battery sizes. However, older Mustangs, like the 1969 Ford Mustang, can accommodate several different batteries rather easily. In the case of the '69 Mustang specifically, a Group 34 or Group 35 battery will fit in what we consider a "direct-fit" situation, where you don't need to modify anything to get the battery to fit in the car.
OPTIMA Batteries actually offers five different batteries that we consider to be direct-fit replacements in the 1969 Ford Mustang. Two of those batteries are the Group 35 battery, available in either a REDTOP or YELLOWTOP and the other three are Group 34 batteries, also available in a REDTOP or YELLOWTOP. However, the 34R REDTOP offers reverse termination, meaning the positive and negative terminal positions are swapped on the battery. Those top terminals aren't that far from being in the center of the battery anyway, but if your cables aren't quite long enough to work with a regular Group 34/78, then the 34R REDTOP could be the difference-maker.
So what about the choce between REDTOP & YELLOWTOP? Generally speaking, REDTOPs offer slightly more cranking amps than their YELLOWTOP counterparts, in exchange for slightly less reserve capacity and the ability to be deep-cycled. What that means for you is that if your '69 Mustang is close to stock from an electrical perspective, then the REDTOP will work just fine. If your '69 Mustang has a car alarm, aftermarket stereo or other significant electrical accessories, then you'll probably want a YELLOWTOP. Either way, if your classic isn't a daily driver, using a quality battery maintenance device will help improve the performance and extend the lifespan of your battery.