i dropped a th350/np203 into my 86 k5. I no longer have a speedometer. i checked the cable and everything, and its still in good working order. what do i have to do to check the drive gear and everything on the np203?

 

You have to make sure that there actually is a drive gear in the back of the NP203. Here are pictures of what you should find back there:

 

well i can tell you thats not what i'm seeing back there. there is an 'L' shaped piece, like an adapter or something, that comes out. the short end of the L is where the cable hooks up into. am i confusing my transfer cases? the tranny and transfer case came out of a late 70's pick up.

 

Here is a picture from a bit further back:


You may have a ratio conversion box on there...

 

That's still not what im seeing lol. the L shaped tube is coming our from the other side and towards the top. ill get a picture taken of it tonight or tommorrow and get it posted on here so you can look at it.

 

Then something is missing... Post up the pic when you get it.

 

Here are the two pictures.

 

Ok, that is close to the same setup as mine. the cover is just rotated 180* and there is a right angle drive on it.

I would disconnect the speedometer cable (what points towards the front of the truck). Then remove the right angle drive. Make sure that the right angle drive is working. With the right angle drive out, remove the bushing which retains the drive gear (what I show in my pictures above). Look in through the hole in the side of the output housing for the plastic drive gear inside.

You can test the speedometer in the gauge cluster by attaching a variable speed drill to the cable you disconnected from the right angle drive. With someone watching the gauge inside, slowly speed up the drill. If the gauge does not work, then the problem is in the gauge.