ABS transmission speed sensor

I have an 86 s10 blazer with a 2.8 v6 and a 4 speed automatic transmission.
Can some one please tell me where the "ABS transmission speed sensor" is located. Thanks for your help.
Why is it called an ABS speed sensor when my blazer does'nt have anti-look brakes? It's also a 4wheel drive.

There is no ABS speed sensor on the '86's. ABS was not avaliable in '86. There is a speed sensor for the speedometer, which is also used by the ECM for torque convertor lock-up, among a few other things. I am pretty sure the '86's still had a speedo cable. If there is a speedo cable, then the speed sensor is located on the back of the dash cluster. If it does not have a speedo cable, then its lacted on the back end of the transmission.

What type of problem(s) are you having?

My check engine light is on and thats the code thats showing. I'm also having problems with the transmission, like not driving when I put it in over drive. or it feels like its slipping. It does slip when I floor it to pass a car. Yes it has a speedo cable.

What is the code number you are getting? Also as for the tranny, make sure you have the proper level of fluid in the transmission and make sure it is not burnt. Now when you say your not getting overdrive, do you mean fourth gear, or no TCC lock-up? Also does it shift fine all the way you until fourth gear? If thats the case, make sure it is filled and to the proper fluid level. If everything checks out, then you most likely have an internal transmission problem. Check and make sure fluid is good first and go from there.

The code number I'm getting is 24. Yes, when I'm saying overdrive I mean 4th gear. It shifts fine till I get to fourth gear then it starts slipping. The level of fluid is fine, but it looks like I need to change the trans fluid and filter. I'll do that this weekend then I'll get back to you.