How do I know which radiator?

I need to replace the radiator in a 98 Trans Sport Montana. There are two core sizes available to me, 5/8" and 1". How do I know which one to get? Thanks for your time.

I need to replace the radiator in a 98 Trans Sport Montana. There are two core sizes available to me, 5/8" and 1". How do I know which one to get? Thanks for your time.
I'm not an expert, but the fact that one is 1" and the other is 5/8" just means the 1 inch probably has more heat exchanging capacity. The key dimensions are the height and width, so it will fit on your vehicle.

Indeed, I think your Florida location would suggest the 1" for better heat extraction.

I gotcha. Thanks for the advice.