Differential Identification?

I talked with the gear shop at Vreins in SLC and they confirmed it is a standard 46k differential and much more info from the tag on the diff.
They said they have modern diffs which would be a direct replacement and made the suggestion they have many used Spicers which would be a direct replacement. Just depending what gear ratio I want to go with.

Talked to Freightliner and the original Diffs were 37k tandems and geared 3.73

They are currently looking to see if they have a newer Spicer 47k with 3.73's.

 

I called the Freightliner dealership and found that the original Tandems were 37k diffs with 3.73 gearing. I didn't ask the brand of the diff. Good idea .

Talked to Vreins gear shop and this differential is a 47k axle and I can almost guarantee it's not 3.73 gears. Way too slow. It's almost geared low enough to make me think it came from a '73 gas powered truck... Maybe an single axle old grain truck?

 

I got home yesterday, and with 2 days on the road, gave me quite a bit of time to think, do some research and call around.

Every shop I talked to asked the same questions, what gear ratio is your old one. I didn't know, but I told them all the same thing.... It's geared pretty low and I want to upgrade to 3.73:1 ratio.

So, I got home and went to the truck to find the gear ratio. It's geared at 4.33:1!
No wonder she was screaming at 65 mph....

The semi salvage yard in SLC doesn't have any in the 3.73. So I did some calling around and in Grand Junction, CO, a truck shop has 2 rebuilt ones (with warrantee) on the shelf and found a company in Orlando, FL which has a few and are $1000 less.
I do my grocery shopping in Grand Junction, and Florida would require shipping, which would probably be more than the $1000 difference.

I'm waiting for a call from a local to see if he has a used one in his boneyard, but it would be unknown mileage with no warrantee.

Looks like I'll be pulling the old diff today. Keep the 1973 housing and just upgrade the gearing.

I'm definitely not a differential guy and this was a learning curve.

Thanks for all the help!