i have a motor that was out of a 79 vette and i put it in a mini pulling tractor and was told that the motor had alot of extras in it but now i have spun a rod bearing and was looking it over and was looking for something to tell me that the crank was forged and could not find anything to should that it was and the rods look stock as well the only thing i could see that is not stock is the pistons they are a set of trw domes so i guess what i am really asking is how can i tell it the crank is cast or forged and tell that the rods are not stock as well and is there any tall tell signs to tell what they are and my next question what is a good set of rod and main bearings to use i have been looking and have found all differnt types tri metal and bi metal etc but really what is differnce in them and what would work best for what i am doing with it thanks
 

The easy way to tell if a cranks is forged or cast, look at the crank flange where the flexplate/flywheel bolts to. On the flat part of the flange, you'll see a parting line. If that line is thin and coarse, you've got a cast crank. If the line is wide and fairly smooth, you've got a forged crank.  

well that be nice it the guy would not have ground that part smooth but the only numbers on the crank is 3941182 and the only numbers i can see on the rod are on the edge of the cap and that is gm on one side and 104 on the other i'm thinking everything is stock cast but i can't find anything on these numbers and i do know that the pistons are trw forged but i don't know the dome size the numbers on them are trw 216 99 if any can help would be great thanks