Here is how to brace a rear axle perch. If you don't do this mod, the perch may tear off! Width is 2.5" length top to bottom is 2.75", 3/16" thick. The hole is not needed, just thought it would look better. Do these front and rear of each perch.
On the right above, I converted my engine stand to hold the rear axle housing for welding and prep. See my "interesting projects" page for more.
This is the 8.5" rear axle I rebuilt. New Eaton posi, Surpior axles, Timken bearings, TA cover, Baer brakes, new brake lines, housing center welded to axle tubes and perches braced to the axle tubes. I also welded a round eye to easily hook tie-down straps directly to the axle assy when the car is trailered. I hate wrapping slings or chains around the axle. Lines were routed to front and rear sides of the axle tube to allow the U bolts to be easily inserted. the baer kit has hose clamps to anchor the outer brake line fittings, I welded them on instead.