STAK 3 speed and Spedo

[sandawgk5]

I was looking on the stak site and I got a question. If I were to put one of these behind say a 465 and put it in my 87K5 with mechanical speedo would I have to get a 90-91 Electric speedo to put in? It seems that the STAK only has electric speedo out.

Any insight on this.

THanks

Ira