Ok, so the racks don’t have part number on them that match the parts computer (RealOEM, etc).
They have tags that look like this:
The top number is ZF part number, the middle number I can find no correlation to, and the stamped number I also have no idea what they mean.
That tag is my original 1991 rack, and this is a used rack Osborne sent me but I have no idea if they are direct swap. It’s supposedly from the correct vintage E30 but the car history is unknown so no idea if it’s original to the 1990 325i (fixed) parts car he took it out of.
I found this PDF from ZF which shows they are not 100% interchangeable but that does not mean they wont’ both work. http://www.unofficialbmw.com/images/steering-flush.pdf
Any ideas how to confirm it will be ok with bolting everything up (requires a subframe drop with our extended oil pan)? They appear to be the same, both are 4 turns lock to lock, pinions seem identical, just slight casting rib differences (very minor) on the main casting so not the same casting tool.
??