Posted By: larrymopar360
Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/25/19 07:26 PM
My '79 W150 has an 8 3/8 rear R&P. It's seeping a bit of fluid from the diff, even though I recently serviced it. I'm going to pop the cap off again soon, and have a closer look to see if the cap is bent along the lip. I don't see any listings for new caps for 8 3/8, so I'm wondering if it uses same cap as the 8 1/4? Randy's Ring and Pinion website doesn't even show listing for one. Only shows 8.25 and 9.25 for '79 W150. I believe both are 10 bolt, so maybe same cap for both 8's? I want to be ready to purchase one if needed. Thanks.
Larry
Posted By: mopars4ever
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/25/19 07:42 PM
Do you need the rubber fill plug? If yes it is the same part number as the 8 1/4 car plug. I have a couple nos plugs. I can mail you one for free if you can`t find it local. 3723687
Posted By: Sniper
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/25/19 08:20 PM
I think he's talking about the sheet metal cover.
Posted By: larrymopar360
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/25/19 09:01 PM
Do you need the rubber fill plug? If yes it is the same part number as the 8 1/4 car plug. I have a couple nos plugs. I can mail you one for free if you can`t find it local. 3723687
I appreciate that but no, I'm talking about the actual cover. 10 bolt cover. Sorry for confusion and Thank you.
Posted By: larrymopar360
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/25/19 09:04 PM
This is all that's listed for covers. Copy and paste didn't work
www.randysworldwide.com/diff-wizard/?diffyear=1979&make=Dodge&model=W150+1%2F2+Ton+4x4&drivetype=Rear+Diff+-+4WD
Posted By: 440newport
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/25/19 11:22 PM
Someone can correct me if I’m wrong, but I was always under the impression that the 8 1/4 and 8 3/8 were one and the same. Just that the 8 3/8 was called that for truck use for some reason
Posted By: mopars4ever
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/26/19 01:22 AM
Easy to find are the chrome ones. The plain metal ones not so much. 4049689. 8 1/4 and 8 3/8 are the same as far as i know.
Posted By: mopars4ever
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/26/19 01:26 AM
Posted By: Sniper
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/26/19 02:02 AM
Dorman 697-709 black steel rubber plug under $30
Spectre Performance 6093 chrome, screw in plug under $25
Posted By: larrymopar360
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/27/19 11:41 PM
I had no trouble finding 8.25 ones. I just need to be sure they are indeed the same (8 1/4 and 8 3/8) before ordering one. What an oddity that Chrysler would confuse things this way if they are the same. My FSM shows 8 3/8.
Thanks.
Posted By: mopars4ever
Re: Same cap for 8 1/4 and 8 3/8 ring and pinion? - 08/28/19 12:26 PM
The mopar part number for the cover is the same for 8 1/4 and 8 3/8. The earlier 8 1/4 part number 2852921 from a 74 passenger car parts book for the cover interchanges with the 8 3/8 4049689 that is listed in the 78 truck book.