I have rebuilt engine with the number 3969854 stamped on the back,I believe it is out of a 1970 vehicle. The back of the engine has Pa99, f-4,gmbL 10-9 also stamped on the back of the block,could any one tell me what these numbers mean?Also it has Hi Per Pass stamped on block. It has a weiand hi rise intake manifold on it. It has truck heads stamped 3975950 on the heads,why would they put truck heads on a 396 engine? What do you think the value of this engine would be,it is suppose to be a 325 hp engine.The plate on the front of the engine was grinded clear when engine was rebuilt.Hope someone can help me to identify and figure some kind of price range.Thanks in advance!!

This casting was made between '69 and '72 I think. Offered in a 2 or 4 bolt main in 1970 only. The rest were 2 bolt. I could be wrong, but the 10-9 should refur to October 1969 for the casting date. 402 cid. It was offered in several hp versions, no way to tell without the suffix code.
I don't no about pricing? Hope this helps some.