Joe,
Can you post a pic or send a pic to my email [email protected] might be interested if is in fact for a R-4.
I can't say for sure it fits the R4, It's from a D4400 engine. Someone who has knowledge of them might know. I can get a picture of it if that will help.
It will not fit the 4400G. The R4 has two different styles that I know of. First is cast with ribs facing the outside & second is the later style that has cast end & center sections mated with tubular steel.