Need Help with T50 Eaton Rear End ID

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I have a 1969 T50 chassis under a firetruck that has an Eaton single speed rear end. GVW rating is 19,500. I am trying to ID the rear end for model number or any other information that would help with replacing the diff.

The glove box sticker lists the rear axle as "Option H21BA, H170, 6.17 ratio".

Crawling under the truck I found the following:
Bottom front of the pumpkin "3826111GM", (likely a casting number) with "D2" below and "276" at 90 degrees to the long number.
Top left side of pumpkin, stamped in "JV1167C2"
Top of pumpkin flange, between 2 bolts, "X"
13 Bolts

On the outboard axle shaft face, "T75" and "S13", each repeated twice, 90 degrees apart. Nothing along the edge of the axle flange.

Anyone know what any of these mean?

Thanks in advance.