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[81GMCSierra1500]

Hey guys...

Recent development on my '81 Sierra Classic. Something went catastrophically wrong in the rear end a bit ago, which caused the pinion shaft seal and diff cover seal to blow, which caused the majority of fluid to leak out... Barely made it home, 2km's or so, thankfully. Oh boy was she growling... Now, the main question. I've bought a decent 10 bolt from an '87 V6 (80,000km's), that needs a wheel seal, and in my attempt to fix it myself, I discovered she's got a broken cross pin retainer bolt, but after all, what frickin' 10 bolt on this earth has one that's not broken... The "hip" that needs surgery is a 12 bolt... Are 10 bolt differentials more reliable than 12's? Especially with this 10 bolt being out of a much newer truck? Also, in recent time before the catastrophic failure, it would make a rather loud and quite noticable "ping" noise when reversed the first five feet in reverse... Bad bearing? Gear teeth contact? It only happened 2-3 times before the seals went... I had hit a pothole while trying to escape a red light left turn, shortly afterwards, put it in park, then reversed, and that's when the growling started. Also, the growling, up until just before I got home, would only happen intermittently, and would start at about 30km/h, and would stop below that... The drivetrain has 260,000km's (161k miles), and the rear end had considerable slack (would shift from park to drive/reverse quite violently if the brake wasn't to the floor). I'm just paranoid, as differentials in good condition are very scarce up here, and I need to know that the 10 bolt is going to be good enough...

Cheers guys!

'81