Q: My ’72 C10 has a TH-700-R4 transmission. I want to run braided AN line to an aftermarket transmission cooler with -6 AN ports. What fittings will I need to adapt the braided line to the radiator and transmission?

IL_16 POD Transmission FittingsA: Your TH-700-R4, and most other GM transmission cases, accept 1/4-inch NPSM (National Pipe Straight Mechanical) fittings. Summit Racing transmission line adapters are -6AN male fittings that thread directly into your transmission case. The transmission cooler on the factory radiator has 1/2-inch inverted flare fittings, so you’ll also need a pair of -6AN male to inverted flare adapter fittings. If you have an aftermarket radiator, you’ll have to identify the fitting size and type to purchase the correct adapters. Follow the diagram when you route your lines, and remember the upper fitting on the TH-700-R4 is the return fitting, while the lower fitting is the output.

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Author: Dave Matthews

Dave Matthews was a mechanic for the U.S. Army, a Ford dealership, and served for many years as a fleet mechanic for construction companies. Now a technical content producer at Summit Racing, Dave has spent decades working on everything from military vehicles to high performance race machines.