Another thing to consider with regard to early brake lines are the soft lines - particularly those that run from the Body/frame down to the axle. On my 75, the soft line did not use a flared fitting. Instead, it used a flat-fitting, and sealed with a copper washer. As a result, the T-fitting it connects to at the axle ALSO lacks a female flared fitting:
This means the long, shouldered, flared lines off more modern trucks will not engage this T-fiting properly. Below, a shot of an old line vs. a new one:
As a result, to run more "modern" rubber brake lines (often done to extend the bake lines for lifts), you will need to find a T-fitting that accepts the propper M10x1.0 shouldered, flared fittings. I just went through this. I ordered a BQ91A T-fitting from BrakeQuip, but the threads were too shallow to accept a shouldered flare fitting. The end result was pulling the (3-way flared) fitting off of an FJ60 parts truck, and running them instead. Haven't installed, or taken pictures yet, but it looks like they will work. These T-fittings are NLA from the dealership, it seems.
Something to keep in mind for those updating their brake likes - be sure to either order the appropriate, FJ40 line for your year (and copper washer to seal), or plan on finding a T-fitting that is flared 3-ways (instead of 2) and deep enough to accept the shouldered, male-flare hose heads.
Not sure if, or when, at some point along the lines, FJ40's started getting 3-way flared T-fittings, but it apparently wasn't in 1975!
