If the radiator is allowing coolant to get to the transmission, it will damage it. Have it replaced. As far as the price, it matters what brand the radiator is. Remember, you get what you pay for. Some of the cheap ones are not worth putting in.

This is where do-it-yourselfers get into trouble all the time. We find parts on the internet at wholesale prices, forget about shipping costs, forget about the markup shops charge in return for the cost of doing the paperwork and to help defray the cost when the part is defective and they have to do the job a second time. You're also forgetting that a rusted-through transmission oil cooler means the transmission is going to have to be flushed and new fluid installed, . . . a second time. The cooling system will also need to be flushed and new antifreeze added. You have to add all of those costs to that cheap internet radiator. $100.00 sounds like a good price for the part. $325.00 sounds like a better value.

I would never order a part like a radiator unless I could see what I was getting. Also, too many parts get smashed in shipping. What does that aggravation add to the cost of the part?