65-70 All Pontiac FS (incl. 65-68GP) rear bearing is p.n. RW508BR, industry-wide. Some mfg drop the "RW".
It really doesn't matter whose brg you use, they all last about 10K miles. It was a bad design having a sealed brg in that application. All the grease "sealed" in weeps out and they run dry. You can extend the life by acquiring a hypodermic grease fitting and squeezing some grease b/t the outer lip of the seal and the outer race every 3-5K miles. That could go on indefinately, but every time you insert the needle, the outer lip gets a little looser, and is more likely to leak...
Stuck in Dallas Tx last May with a broken posi and a bad whl brg, I was forced to improvise. The 4.11 posi was swapped for a 2.73 open in the pits, but the axle brg presented more of a problem. So, to extend it life and get home, I removed the inner lip seal (inside face of brg) and loosely packed the recess b/t the axle oil seal and the inside face of the brg with whl brg grease. This insures a constant, greater volume of grease to lube the brg. The only prob so far is slight weeping of grease around the OD of the brg. It's not even enough to make it onto the backing plate. I'm sure this is due to windage, not actual leakage. A small hole in the top side of the axle tube with a 1/8" NPT nipple fitting, some vacuum hose and a check valve should eliminate any weepage around the brg. (I have yet to do the last mod, but plan it soon.) It's my hope that the next set of brgs I buy will be the last.
Arowhed, next week... no later.
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Jeff Ianitello
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