Dana 80 ring and pinion kit

[dangerous06]

hey guys cleaned out the garage and found this kit for a second Gen 98 Dodge ram with a Dana 80 3.54 gears with bearings. Original Spicer kit paid 1200. for it still new never used make me an offer! Label says for 4.125 OD
ONLY! What ever that means!

 

[dieseltracks]

Label says for 4.125 OD

I think it pertains to the pinion shaft diameter.

I think there is a 4.125 and a 4.375.