I am still wondering if these pipes will fit Caprices and Impalas.
Seems like no one knows for sure, so I will wade in...
My recollection is that the Monte Carlo has the mufflers in the same place as the full-size cars (unlike the Cutlass which had the muffler tucked tranversely behind the rear axle). These mid-sze cars were setup similar to the full-size cars, but on a slightly smaller scale.
If your question is whether you can put the tailpipes on WITHOUT MODIFICATION and have them fit right, I would bet that the answer is NO.
If you are asking whether you can put them on WITH A LITTLE MODIFICATION and have fit right, then I would say "most likely yes". The key as to whether or not it is a good decision cost-wise is whether you have a good muffler shop around that is not a chain shop (Midas, etc.). Most of these smaller shops will take little projects like this and not charge an arm and a leg to do it.
Let us know how it turns out.