here is a pic of a c-7 cat. in a ford f-350. If it will fit in there it will fit in an m-715.



In the picture you can see that it clearly has a cut firewall to get it in there. The c-7 and 3116 are the same dimensions with the exception of width, the c-7 is wider. Thus making it a tighter fit. Clearly possible. Snakeater