The good old days.
i have 5.13's in my axles. I believe 5.38 requires some clearense inside the 14 bolt housing. It still drove fine with 38.5 on H1's with 5.13 on my 20R/w56/stock duals combo.
I opt to just redo all my brake lines from scratch. Made my own adaptor plate to mount my Chevy master cylinder to my yoda brake booster.
running a T fitting in the middle of my axles I eliminated my brake lines that tend to get in the way coming off the brake calipers. Did that to the front and rear of my rig.
I have a brake proportional valve in line to adjust rear braking.
rears up front minus the over load spring and added to more leafs making it a 5 pack. Anything less was to soft and bent the two main leafs. Made my own drop hanger and later extended for my one ton swap. Made my own shackles that are off set as well. A quality flare kit is a must. I tried autozone tool they sell and it just ducked big times to get a doable flare that would seal properly.
1980 Toyota 4.3/465/300 on Propane.
60/14 welded front, detroit rear 5.13 gears.
39.5 IROC on H1's