I see that Forte makes a converter so you can use a normal GM f-body speedo cable. Seems like the right way to do it but 60 bucks is pretty steep for this little thing. Are there any other options?

I happen to have a speedo cable that fits the TKO, but the other end is a screw-on style, and the thing isn't nearly long enough to reach up in behind the dash. Don't know what good it is to me unless there's something out there to go from this screw-on style to a GM clip-on to go into the gauge.

 

I'm not understanding your problem. my stock cable screwed right up to my TKO600.....

 

Forte is the only one that makes the mechanical adapter. If you have the stock speedo, a cable for an 87 Camaro will work. The other option is to get a aftermarket electronic speedo & use the electronic speed sensor that comes with the TKO. Although that would cost more than $60.