SB
Is what it says, works as it says.
Worked for what I needed. Guy I bought an xj off of had his blown up diff serviced and the guy put the factory carrier back in with 4.88 gears. Lovely to find that out as I'm trying to shim this thing and not getting anywhere close. Well we figured it out eventually and slapped all the guts into this thing and it fixed it right up. And it's Yukon so I feel good about it.