76olds

I had my TH350 rebuilt last summer and put in a TCI Saturday night special T/C , I would like to add a trans cooler in front of my rad. My question is... Would I need more than a 17,000 lbs? I just wanted to order the Summit brand. I'm not sure what I would need. They go from 17,000 lbs up to 30,000 lbs, not really sure what to purchase.
Thanks
Eric