I purchased a 1985 GMC Vandura 3500 vehicle. The seller told me it was not the original motor ( he cannot be found now ) I don't know if it was rebuilt, changed or what. I have the original specs but found the spark plugs are not what the specs say they should be. How can I determine what motor is in the vehicle ? If I have to look for numbers where do I look, and then what do I do with them. Thank you

 

I forget what year it started, but a lot of later GM blocks are labeled on the back of the motor on top by the bellhousing, Youd probably have to take your dog house to see it though. Id have someone who knows chevys to take a look at it.

 

idk mang

 

the block should be stamped, just run the numbers through google, you'll find it

 

also if you're just worried about plugs take one out and take it to the part store there should be a part number they can cross-reference to get you new plugs