I'm looking at the wiring diagrams on Autozone.com, and they show a part called a "digital radio adapter control" connecting to the PCM. It has inputs from the instrument cluster, cruise control, and the VSS. I'm guessing it's the little white box attached to my PCM, which is the other thing I was about to come here asking about, lol.

Just curious what it's for/what it does?

 

Well... Lets start with your vehicle information...

 

'91 S10 Blazer 2WD, 4.3L Z code, TH700-R4, equipped with cruise.

 

Ah. What you are talking about is the DRAC module. It stands for Digital Ratio Adapter Controller and it is used to calibrate the speedometer as well as control cruise and ABS (if so equiped).

THIS SITE gives more information on what you can do with it.

 

Ooooohhhh....RATIO! That makes MUCH more sense, lol

That is a nifty little thing, especially the ability recalibrate it. That will save a good amount of money when I change gears in this pig, thanks!