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.
Eaton does not supply left hand thread ring gear bolts with their
units, if you need ring gear bolts, DO NOT buy bolts with the SMALL
5/8" head! GM uses a special 3/4" large head bolt with tiny "stair
steps" in the underhead seat, this keeps them tight and supports the
bolt. The 5/8" headed bolts only have .062" seat under the head and
it will sink into the softer cast iron carrier after a while and come
loose. When it comes loose, it will back out and be sheared off by the
carrier bearing caps. Use GM #
1241564, or Mr Gasket bolts. I haven't been able to find ARP bolts
for this axle. Bolts are 7/16" 20 X .850" LH thread. In a pinch, I have
been told you can use grade 8 washers under the heads of the 5/8"
headed bolts, but play it safe if you can with the proper GM bolts.
Here is a Ratech bolt from Summit with the "small" 5/8" head.