Chevy & GMC Vans

I had this digital dash for some time sitting on the shelve and i have read some few articles on doing the swap from an Analog to digital into my sweet 94 Astro van, i will also change the colored film to make it look better than green,

Now i have a mind boggling question for ya. the main harness shouldn't be a problem to figure out the pin outs and all, but there is another one that i have no clue what it does and i was wondering if anyone could shine the light on this.



Here is another pic of it


Another question as soon as the dash will be swap, is there a way to reset the mileage of the digital dash and put the new data in for the actual mileage of my Van? the digi dash have about 145,000 km and the actual mileage of my van is 475.000 km.

Thanks

I say keep the younger odometer reading

LOL

True, but i am not selling the van anyway. she is mine until it is totalled By the insurance company.