or does it even matter?

 

Not a good idea.... They really should both be replaced at once. One bad battery can ruin the good one.

I see your from Texas. Since you won't be dealing with super cold start issues. If you really for sure can only afford to get one battery at a time you would be better to remove them both, put one new good battery in and then get another as soon as funds allow.

I believe there are a few on this board that only use one battery in their second gen.

 

Seperate the two batteries by disconnecting the big cable between the two and do a load check on each one individually (Advance or somebody like that will usually do this for free). This will tell you which one, if not both, is bad. I have found out on the last three trucks, the right one usually goes bad first. If you really can't afford two, then if the right one is bad, move the left one to the right side and install the new one on the left (drivers) side. It seems to be the one that lasts the longest for whatever reason and seems to get the most load. Either way, I would put the new one on the drivers side if you really must do it this way.

 

spring for an optima red top, throw it on the drivers side and thats probably all youd ever need in Texas....

 

Houston yes, Dalhart no.

 

I thought about Optima's but will go with sealed lead acid instead and replace both at the same time.

 

My son ran the battery in his old 81 Dodge for almost three years after I took it out of my truck. The left one usually holds up for a longer time for whatever reason.

 

Does he really even need 2 in Texas? I believe 1st gens only came with 1 and they start fine up north in the cold. I bet a good single would be plenty. You need to look at cold cranking amps. Get the biggest possible. If your into modifying the battery box a group 31 would spin a CTD great. Don't know how much they cost.