I think I'm gonna be sick

[Mopar Man1]

Ya I'm the moron that knows nothing about Cummins and bought a new to me 91 D350 Cummins truck. When we went to look at it,the owner said that it had developed a oil leak,said it was not bad at all. Went and looked at the truck and the mount that the oil filter mounts to,it was leaking around that bracket and the side of the motor. I believe it is just the gasket behind it that is leaking. We didn't let it sit and run a really long time but did a little bit. Shut it off and everything ran like a top,said it started leaking after sittin and idling about 30 minutes when someone else was looking at it. Bought it at a deal cause of that leak and now it's home. I'm learning as I can as you could tell from my other post,but I've been looking at the truck from top to bottom. I popped the radiator cap off cause I didn't ever check it before,look down in it,it looks to be just a little low,but I can see it and its green so its got anti freeze in it. Look at the bottom of the radiator cap and... I believe its got oil on it! I felt of it and it was greasy kinda like oil,smelt of it and it smelled mostly like antifreeze,pulled the dipstick,smelled of the oil and they didn't really smell the same...but anti-freeze isn't a gray looking greasy substance....the truck only has 119k on it,but it was used by contractors so it was used hard. The other owner started to get it ready to paint then stopped. So I still gotta fix the oil leak,need to find out how many quarts of oil to use and what kinda oil filter to use from yall(any help on that?) But I think I've got a killed head gasket or something..cause I believe I got oil in the water

Jimmy