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How to tell which differntial I have #1662268 08/22/14 12:23 PM 08/22/14 12:23 PM
Joined: Mar 2004 Posts: 143 Crofton, MD B bri440 OP member
bri440 OP member B Joined: Mar 2004 Posts: 143 Crofton, MD	Don't know much about identifying the various Mopar differentials. I have a 71 Challenger 340 RT. Always thought I had a 8.75 differential. The pinion seal was leaking, so I bought replacement seal. The outer diameter is too small. Measuring the differential shows an opening of about 3.1 inches. All the parts websites identify a Dana differential as having a 3.165 seal diameter. The 8.75 has a 2.815 diameter. How can I identify which differential I have? Thanks,

Re: How to tell which differntial I have [Re: bri440] #1662269 08/22/14 12:32 PM 08/22/14 12:32 PM
Joined: Jan 2003 Posts: 4,696 enfield, CT ViperDave master
ViperDave master Joined: Jan 2003 Posts: 4,696 enfield, CT	http://www.crankshaftcoalition.com/wiki/Mopar_rear_axle_spotter's_guide Pictures and descriptions and casting numbers 67 Dart GT Vert 273/904 72 Town & Country 440/727 90 D350 reg cab dually cummins 15 Scat Pack Challenger

Re: How to tell which differntial I have [Re: ViperDave] #1662270 08/22/14 01:04 PM 08/22/14 01:04 PM
Joined: Jul 2009 Posts: 794 massachusetts U.S.A. 1 1969ronnie super stock
1969ronnie super stock 1 Joined: Jul 2009 Posts: 794 massachusetts U.S.A.	bri, 2 size pinion seals for the 8.75. you need one for a "742" case 8.75. what case number on the side of dropout? 741, 489, 742 ?ronnie

Re: How to tell which differntial I have [Re: 1969ronnie] #1662271 08/23/14 10:47 AM 08/23/14 10:47 AM
Joined: Mar 2004 Posts: 143 Crofton, MD B bri440 OP member
bri440 OP member B Joined: Mar 2004 Posts: 143 Crofton, MD	Thanks for the info. It's definitely a 8.75 rear end. Haven't crawled back underneath to look for the stamping. Thanks again

Re: How to tell which differntial I have [Re: bri440] #1662272 08/23/14 12:03 PM 08/23/14 12:03 PM
Joined: Jan 2003 Posts: 42,714 Spokane Washington ScottSmith_Harms Mr Wizzard
ScottSmith_Harms Mr Wizzard Joined: Jan 2003 Posts: 42,714 Spokane Washington	You are looking for a CASTING number, drivers side, lower forward area. The last 3 digits are the key "721" "489" "742" etc. 8249194-rear%20003.jpg (76 downloads)

Re: How to tell which differntial I have [Re: bri440] #1662273 08/23/14 01:55 PM 08/23/14 01:55 PM
Joined: Aug 2003 Posts: 43,127 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,127 Bend,OR USA	Quote: Don't know much about identifying the various Mopar differentials. I have a 71 Challenger 340 RT. Always thought I had a 8.75 differential. The pinion seal was leaking, so I bought replacement seal. The outer diameter is too small. Measuring the differential shows an opening of about 3.1 inches. All the parts websites identify a Dana differential as having a 3.165 seal diameter. The 8.75 has a 2.815 diameter. How can I identify which differential I have? Thanks, If the third meber drops out the front it is a 8 3/4 ,if it doesn't, it isn't Look for the casting number on it for the correct seal I have seen 7 1/4, 8.0, 8 3/4 and 9 3/4 Dana in 1970 and 1971 Mopars Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

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