Speedometer/VSS question

[84GNwith87eng]

Converting gauges to vdo analog gauges, I do not want to throw a VSS error code, which of these do I need to do this?

https://www.casperselectronics.com/...creen=PROD&Product_Code=102046&Category_Code=

or this

https://www.casperselectronics.com/...creen=PROD&Product_Code=102047&Category_Code=

Just confused on how they interface with my existing speedo cable and whatnot...and if I will still throw an error code.

Thanks

C