[Tx Firefighter]

Drum brake trucks mounted the hoses and lines on the rear side of the crossmember.

When GM went to disc brakes in 71 the entire layout changed and the lines and hoses go to the front of the crossmember.

There is absolutely no way the crossmember is backwards.

The easy button is calling ECE and telling them you need a pair of front brake hoses for converting a drum truck to discs. They sell special conversion hoses for this exact scenario.