This makes 3 steering boxes, 2 from Iroc/Z28 cars and 1 from an 87 GTA that are not XA XH marked. The only differences are, one box is stamped 150 on the aluminum cover, and 1 is stamped 201. The rusty one I just pulled from a low mile loaded 88 with G92 option. I thought for sure it would be the 12:1 ratio. Odd

 

The ink stamps are commonly gone, wear and weather takes a toll on them. Also, check the front end cover of the box too, they are usually stamped there.

The other way to tell is it is a fast ratio box is to remove the top cover, turn the input shaft to expose the worm gear, and look for the number of thin grooves in it. Two grooves is a fast ratio box. These grooves are between the ball grooves, on the high portion of the worm gear.

RBob.

 

I knew I posted a pic of this here:

https://www.thirdgen.org/forums/susp...ml#post2195662

RBob.

 

Oh man, if I pull that top cover, I'd be afraid I wouldn't know how to put it back together with that lash/tension nut

 

Those aren't "stamped".

They're CAST into the cover casting. Most probably some sort of plant / date / shift /mold-cavity kind of production code for that individual cast/molded part, long before it was assembled into anything.

Worthless for identifying which guts are inside.

Any "stamping" info is contained in those numbers that are ... STAMPED ... into that large raised flat rectangular area. Unfortunately I have not the vaguest clue how to decode any of that. The "Xx" designations were on a white label that also had a bar code. Doesn't seem to survive a "rebuild" most of the time. Seems like it has been destroyed on both of those in the pics.

 

Oh I don't know about a white label. The ones I have seen are ink stamped on the front and some times on the 4 bolt cover.

 

I guess I'm confused by your original post. You said none of the three you have are stamped XH, but in your most recent post you're showing a picture of one stamped XH.

I have a spare one stamped XH. I got it from Tom at House of Camaro in Los Angeles back when he was still in business in the 2000s. He was a 3rdgen dismantler and said it came off of a low mile WS6 Trans Am. I'm not saying it's available, just confirming the code. It's been on my shelf for 15 years waiting for the day I need to replace my original.

But here's a thread where James, in post #2, lists the codes and ratios. It confirms XH as the correct code for a 12.7:1 steering box, and so do other members further down in the thread. James also lists a WS as possibly an earlier version of the generation's 12.7:1 box.
Power steering Gear Box - Third Generation F-Body Message Boards

 

Oh that was just a picture from Google

 

I spoke too soon. I just looked at the one I pulled out of my 88 and when I look at it in the sun, I can see the faint XH ink stamp on the end cap.