Ok. I did the search, and i'm still not finding the info that i want. I have just purchased a 68 396 for my 71 chevelle. On the back of the engine it has a casting that says hi-perf truck pass. What does this mean? Just speculating i believe that hi-perf pass means it's a low /standard deck block, and the truck designation means its a 4 bolt main also. Is there anyone out there that can clear this up for me? Your info has been invaluable in the past. Thanks.

www.mortec.com (http://www.mortec.com)

Thanks for the info,but i've already looked at www.mortec.com. (http://www.mortec.com.) The info on there was accurate as far as the serial #. But concerning the casting designation its pretty vague.

There are other things found when you stare at these parts and casting identifiers for a while. On big blocks, you may see the words "HIPERF", "HIPER", "TRUCK", "M.TRUCK", "PASS", "MAR" or "MARINE" cast into the block. You may see one or a combination of some of these words. First let me say that "HIPERF" or "HIPER" was used on ALL '65-'91 Mark IV big block blocks and is not an indication that it has four bolt main caps and was used in a high performance application. Two-bolt, low performance big blocks received the same "HIPERF" designation. (In this regard, keep in mind that ALL '91 and later Gen.V and Gen.VI big blocks come with 4-bolt main caps. The two-bolt big blocks are no longer in production.) These same words can be found on the head castings also. Usually the "HIPERF" casting on a head indicates a rectangular port head, but I have found one large oval port head with "HIPERF" showing in the rocker arm valley. This was head casting number 14092359 and was off of an '87 tall deck 427 truck motor.

from www.mortec.com (http://www.mortec.com)

Nevermind. I found the answer in the engine archive. I've got to get better at using the search feature. Thanks for the input.