143 is for old school carb engines, 160 is for the modern carb engines and EFI's, and 180 is for closed cooling. The 160 is the one to go with for better idle quality and performance. I bet that 180 T-stat sure made alot of steam on a cool day with it running.

Ferm beat me too it, I personally never ran the 180s in a closed system(160 on 1/2 cooled, 143 on completely ccoled), I always used the 143 on carb motors, 160 on EFI( you can do more damage running an EFI cold than hot)

Glad the hose were the right size, it can get expensive replacing molded hoses