I got 351M according to the vin on the 69 gmc medium duty. Through a rod but the hole is the oilpan and not block. Plus is broke part of the piston skirt too. Got some questions I need answered so I get this back up and running again.
Does the medium duty trucks have 3 or 4 pistons rings? If 4 ring will a 3 ring piston work? Know of good parts source for parts for this engine?
I found some 305/351M v6 parts for them here
http://www.mecanicapedrosa.com/