I used a TS1000 on a 3/8" line a few years back. The application I used at that time said it was correct for 3/8". I know it was a very very tough go getting it onto the line but that is the way you would want it. You don't want it falling off.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars