The gauges on my 68ss/rs aren't working. i have a speedo and fuel gauge. i can't seem find a fuse for them. i do have all working dash lights.

Secondly, my car has a 4 speed muncie transmission. I'm not sure if its an M-21 or 22. I know the M-22's reputation as the "Rockcrusher", but how can i verify?

 

Those old spedos were mechanical, so no fuse for them. The fuel gage is electrical, so it should be fused somewhere, although it may not have a dedicated fuse.

 

The gas gauge is on keyed power. I can't remember exactly which circuit it's on though (should be "gauges"), but it's not on it's own dedicated line. One side of the gauge should be hot with the key on, and the other side gets connected to the sending unit which gives it degrees of ground (E-F). If you ground that connection to the body, provided it's getting power, the needle should peg. If not, the gauge is bad. If it does, your line/connection to the sending unit is bad, or it's the sending unit itself.

 

If your tranny was manufactured after oct 68 and you can find the code it will have a type suffix at the end. Example: P9T11B, The B at the end being an M-21. A is M-20, C is M-22. If it does not have a suffix code you need the maincase casting and count the ring grooves on the input shaft. Example: 3925661 with one shaft groove = M-21.

 

the easiest way to tell if its a m22 is does it make a lot of noise when driving and shifting. thats why they are called rockcrushers they sound like they are crushing rocks. i alos think they have the bigger output shaft or i might be confusing that with a super T-10

 

Awesome. I appretiate everyones input