8 3/4 rear id help?

[bmoparmofo]

Hi, I need some help getting an id on this rear. I know there are 488 and 489 castings. Is this missing a number on the casting? I am also curious about the suregrip unit. Its a 3.55, is it a clutch type or? I havent really messed with the rear on these before so I am pretty ignorant on the topic. It is a small yoke, my driveshaft has the larger ujoints. I read that there is an adapter ujoint out there that would work to go from the larger one on the driveshaft to the smaller yoke on the rear? Anyone know if they work alright? I will attempt to link the pics here. Thanks for any help, I appreciate it!   

[John_Kunkel]

You have a 489 housing, the complete number is 2881489....somebody at the foundry omitted the 9 in the mold (you can see the divot in the casting where it should be) but the single 9 higher up on the housing also ID's it.

The Sure-Grip unit is the cone type. Behind the P/N and ratio stamping on the ring gear you will find a date which will give a clue to its birth year.

[bmoparmofo]

Thanks John