Now that we have all of that established...
The color in Automotion that matches the '88 Grey-Beige / Light Grey color (Interior code XP) is #923, with paradoxically is called "Linen" by Automotion
Here is the information on the sample:
883417
#923 Linen sample
198328 Performance Products 800-752-6268
I guess you can't trust color names from a company that can't decide if they are Automotion or Performance Products, LOL
Cheers, Keith