Which diff do I have?

Mike Arnold · Jun 24th, 2024, 13:01

I am trying to identify my diff but it does not seem to have a manufacturer's label (maybe corroded off) or a number stamped on it. However, the casing is a mix of rust and underseal so not that surprising. Here are a couple of photos for the experts out there. Thanks.

142 Guy · Jun 24th, 2024, 16:00

In 1967 Volvo started using the Dana 30 so your 1966 may be a Dana 27 (technically Spicer). The tell is the OD of the axle tubes. Dana 27 is 2.25" and Dana 30 is 2.5"

Mike Arnold · Jun 25th, 2024, 13:18

Thanks to Saskatchewan (I will raise a glass to you when I am over in Ontario in August seeing family).
Someone told me that if it has a backplate then it's a Spicer (or similar) so I hope it is as the others are difficult to get parts for.
I will take your tip and measure the OD of the axle tubes.
Mike

142 Guy · Jun 25th, 2024, 16:20

Spicer is Dana! Or more probably Spicer became or was purchased by Dana. Spicer remains a current entity and in 'Dana corporate speak' Spicer appears to be the trade name for the ring and pinion. Dana corporate speak refers to Spider ring and pinions being the genuine R&P in all Dana back axles so Spicer versus Dana is not a good discriminator.

Short answer is that the parts availability may be more related to the 27 back axle being older than the 30 axle and the 30 axle seemed to have a wider usage. Seals and bearing for the 27 appear to be commonly available. Replacement ring and pinions appear to be un obtanium. Some differential specialists (like Yukon Gear) appear to sell the spider gear and carrier assemblies for the 27; but, you have to be careful because the 27 family was used on the front axle of some 4 WD products and that differential is not the same as the 27 used by Volvo.

If you have a 27 rear axle, shopping around for a later 30 axle from a salvage vehicle might be an option.

Derek UK · Jun 25th, 2024, 18:29

1966 122S - If it came from the factory with the M40 4 speed it will be 4.10. If it has a M41 with factory overdrive it will be a 4.56.

Mike Arnold · Jun 26th, 2024, 08:34

Thanks. It has overdrive.

Mike Arnold · Jul 3rd, 2024, 10:40

Just measured the diameter of the outer shafts and they are 64mm (2.5in) so this must be a Spicer/Dana 30 back axle. Thanks for your help.

Jun 25th, 2024, 13:18	#3
Mike Arnold Master Member Last Online: Jul 9th, 2024 09:34 Join Date: Dec 2001 Location: Stockport, Gtr Manchester View Photos By: Mike Arnold	Thanks to Saskatchewan (I will raise a glass to you when I am over in Ontario in August seeing family). Someone told me that if it has a backplate then it's a Spicer (or similar) so I hope it is as the others are difficult to get parts for. I will take your tip and measure the OD of the axle tubes. Mike __________________ Mike Arnold. 1966 122S

Jun 26th, 2024, 08:34	#6
Mike Arnold Master Member Last Online: Jul 9th, 2024 09:34 Join Date: Dec 2001 Location: Stockport, Gtr Manchester View Photos By: Mike Arnold	Thanks. It has overdrive. __________________ Mike Arnold. 1966 122S

Jul 3rd, 2024, 10:40	#7
Mike Arnold Master Member Last Online: Jul 9th, 2024 09:34 Join Date: Dec 2001 Location: Stockport, Gtr Manchester View Photos By: Mike Arnold	Just measured the diameter of the outer shafts and they are 64mm (2.5in) so this must be a Spicer/Dana 30 back axle. Thanks for your help. __________________ Mike Arnold. 1966 122S

Jun 24th, 2024, 16:00	#2
142 Guy Master Member Last Online: Yesterday 22:25 Join Date: Jul 2020 Location: Saskatchewan, Canada	In 1967 Volvo started using the Dana 30 so your 1966 may be a Dana 27 (technically Spicer). The tell is the OD of the axle tubes. Dana 27 is 2.25" and Dana 30 is 2.5"

Jun 25th, 2024, 16:20	#4
142 Guy Master Member Last Online: Yesterday 22:25 Join Date: Jul 2020 Location: Saskatchewan, Canada	Spicer is Dana! Or more probably Spicer became or was purchased by Dana. Spicer remains a current entity and in 'Dana corporate speak' Spicer appears to be the trade name for the ring and pinion. Dana corporate speak refers to Spider ring and pinions being the genuine R&P in all Dana back axles so Spicer versus Dana is not a good discriminator. Short answer is that the parts availability may be more related to the 27 back axle being older than the 30 axle and the 30 axle seemed to have a wider usage. Seals and bearing for the 27 appear to be commonly available. Replacement ring and pinions appear to be un obtanium. Some differential specialists (like Yukon Gear) appear to sell the spider gear and carrier assemblies for the 27; but, you have to be careful because the 27 family was used on the front axle of some 4 WD products and that differential is not the same as the 27 used by Volvo. If you have a 27 rear axle, shopping around for a later 30 axle from a salvage vehicle might be an option.

Jun 25th, 2024, 18:29	#5
Derek UK VOC Member Last Online: Today 13:44 Join Date: Jul 2006 Location: Chatham	1966 122S - If it came from the factory with the M40 4 speed it will be 4.10. If it has a M41 with factory overdrive it will be a 4.56.

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