Chevrolet Repair: 1987 Chevy R10 Pickup Trouble Code 24, stock tranny, 700 r4

Question
I was able to retrieve the trouble code "24" from the vehicle but when i crawled under to look at the speedo, i found it was disconnected. This was no surprise because the speedometer was not working. The problem is the piece attached to the end of the cable at the trans is a screw on connection like a typical speedo but the trans has a speed sensor in the tail shaft with a 2 prong connector. What do you think is missing and where could i find this piece to correct this?

Answer
what it sound like to me mark is that someone has changed the stock tranny (prob. a THM 400 or a THM 700-R4)for a 4L60E (electronic). you might be able to remove the speed sensor and put in an after market speedo drive gear and retainer. your best bet for those would be at an auto wrecker. not 100% on this question sorry mark.