What is the deal with the different length stay rods I see noted at some parts sites? One of them specifies a different front bushing, and I've read about fitment problems with some poly front bushings depending on stay rod length in the FAQ as well.

Edit: see here..
http://catalog.autohausaz.com/autohausaz/detailw.jsp?sid=2lvn4nbvvul5xyzzdtaa1z45&partner=autohausaz&year=1987&make=VO&model=740-T-001&category=L2044&part=Control%20Arm%20Stay%20Bushing

Different length rods available to adjust caster while aligning front wheels. Aprox 1 degree caster change between shortest and longest rods.

740 85-92 Control Arm Stay 388.5mm AFT 6819079

740 85-92 Control Arm Stay 385mm cars with 16 in rims 1387066 OEM 3530790

740 85-92 Control Arm Stay 390.5mm not for 16in rims 1359899 OEM 3530789

So, there are three.

A short one, an "updated" middle length one, for cars with 16" wheels?
And a long one, "not" for cars with 16" wheels.

Now, I need to replace these on my 15" wheel'd 87, that might one day have 16's.
I don't really want to order three sets, or to have to make possibly three trips to the alignment shop to find out which one's I need.

Is there any sort of rule of thumb here? I guessing the mid length ones.