700R4 VSS to cable speedometer

[thewr3tched]

This is in an 86 C10. It came with a 700r4, but I'm not 100% the one in it is original. When I got it, the speedometer housing in the tail section was missing the driven gear and just had the regular mechanical style housing. Turns out, the output shaft on the trans doesn't have a drive gear and only has the VSS ring.

i'm guessing this used to have some way to convert the electrical signal to a mechanical speedo or maybe this trans came from a later model truck and didn't need the mechanical output.

it looks like i'm going to either need to pull the vss ring and convert it to gear driven style, or try something like this: http://www.summitracing.com/parts/RPC-250-4153/

has anyone used something like that? or are there some factory replacement parts i can use to make this work? might be easier to just convert it to all mechanical.