Need to ID my steering gear

[jrdrag]

I have a 98 Chevy 3500 crew cab single wheel one ton with a 5.7 vortec. I need to identify what series the steering gear is. I don't think it's a series 500.

 

[Schurkey]

I just looked in the '97 service manual, I can't find any mention of what model the steering gear is.

They don't differentiate among half-tons, three-quarter tons, and one-ton trucks, either.