Depending on what you mean by "repair", the common issue for a speedo not working in an 80s Monte, is due to a bad cable, which would just need replacing. Your question needs a little more detail.
Monte Carlo Automobile was created in 1983.
NO. Not even close.
There is no such thing as a 2008 Monte Carlo, so the answer would be no.
Yes
pick up a chiltons repair manual from the library for your car.
Around 4700
No
15 miles per gallon
I believe so, but I'm not positive and I'm not a mechanic.
it all depends on the amount of horse power it has,most made in 1983 have horsepowers of 110.
If the speedometer is not working it probably needs a new speedometer cable. If the speedometer is actually broken either take it to as speedometer repair shop or replace it.
there is a set screw on the linkage on the carb that will adjust it.