diff compatibility
 

I know this is a perennial topic, but I can't find the info I'm looking for. I've been chasing bad bearing noise for a while now (not localized, low speed, wheel speed related, not engine speed). replaced all the wheel bearings, complete front diff, and more. basically I've decided it's in the transmission/transfer case.

anyway, as part of my "replace everything" philosophy, I swapped rear diffs. truck is an 88 v6, but a buddy had an 85 front that he gave me for free. customer of his services it, then changed to a high pinion locker, so it's like new. I figured I'd run with it and rebuild my v6 third as a spare. I checked spline count and satisfied myself that it really was a direct swap. I was stoked.

then I put it into my rear end, and now my axle shafts won't fully seat. question is: are my axle shafts too long for this diff? is the cross pin rotated such that they don't seat properly? I got fresh gasket maker curing on it and I hate to pull it off just to look. what am I missing here?

ian.

Did you make sure it was the same gear ratio? But that shouldnt matter on the shafts seating. How much farther do they have to go before they seat? Pictures always help.

it's like a quarter inch each side. same each side. really close, but it's a metal to metal clank when it stops. shafts are really not going in any further. i guess i'll be pulling it back out now that my gasket is fully cured. meh.

ian.

update: the 4cyl diffs are not forward compatible with the v6 variety. at least this one isn't. the crosspin doesn't have flats on it for the v6 axles to seat on. measured with calipers, I'm definitely seeing a difference of about .150" on each side, which was what I was seeing at the axle mounting plate. not that this is a big deal since I imagine nobody usually wants to replace the 4 pinion diff with a 2 pinion one.

ignore everything I've said. better yet delete this thread. I don't believe I was doing it right. I put yet another diff in and I dot think I was letting it pull up with the hardware. but I'm not willing to pull it all apart again to see if the other diff works. don't believe anything I say about doing something until I've done it at least twice.