Anybody have an idea what ratio rear this is?(pics)

[bmoparmofo]

Its a 489 case, The person said its a 3:91 suregrip, I dont have this part number listed in the only book I have. He said it doesnt have a ratio stamped on the gear but it has this part number....

[mikepmcs]

Rob,
The only thing I can tell you about the pics on this is that it is a cone style suregrip vice a clutch style and that is the desired 489 case.
Cone is the lesser desired of the 2 SG units because of the complicated rebuild on them.  It can be done but requires some machining. Check this out.

http://www.moparts.com/Tech/Archive/axle/13.html

Can't tell ratio from those pics but it the ring does appear to have more teeth than a higher ratio.  I assume it has a 10 tooth pinion so if that ring gear has 39 teeth then it is possible that it is a 3.91.   I did a quick count on the pics from what appeared to be half to me and cam up with 20, so 20x2 is 40 so it's probably close.  My only concern is the low gear ratio and the cone SG meaning   I'd be weary about the service life left in that SG unit.

He should be able to spin that ring gear and the ratio will be stamped on it to the left of the part number.

One last thing, if he is pretty much giving it away, then you can't go wrong you just might have to spend some time machining the cone to make sure it is gonna give you a good service life.

is he telling you this is a stock gear set that came with the 489 case or is this something that was added into the chunk aftermarket(ring and pinion)  If so you might have to find the manufacturer of the ring and pinion to id that part number.

v/r
Mike

[Heck2G14]

count the amount of teeth on each gear then post it we should be able to figure it out from there.

[John_Kunkel]

1673362 is the part number of a 4.10 ring gear used in the old 985 housing, this is used with the 1 3/4" pinion prior to '64.

Looks like a blend of different year parts, I'd love to know how they got a 1 3/4" pinion in a 489 case setup for the 1 7/8" pinion. Hopefully they didn't mate a mismatched ring and pinion.

[bmoparmofo]

Thanks john, that is very helpful as the person thought he was selling a 3:91, Thanks again!