Block codes & Head codes

We have a 1968 GTO and it needs a motor but we doon't know which one would be the best motor to rebuld. Both are in need of total rebuld.

When standing infront of the block in the left upper conner the two digit code on one of the engins is "WZ". Then on the second motor the block code is "YD".

Standing in front of the motor "WZ" on the LH. side of the timing chain and water pump cover is vin 28P which we believe means its a 1968 block.

Standing in front of the second "YD" motor on the left hand side of the timing chain and water pump cover is 20P which we think means 1970 block. The 1970 block is drilled and tapped 4 bolt main caps but dose not have 4bolt name caps installed they are 2 bolt.

Can anyone tell us by these numbers what size the motors are and what they came out of?

Here is a link to a site that will decode the blocks for you.

[www.wallaceracing.com]

The date code is on the rear of the engine, to the driver's side of the distributor hole. It should start with a letter, and then 3 numbers will follow. The letter signifies the month (e.g. A=Jan, B=Feb, ect.) The following two numbers signify the day of a month, and the last number is the last number of a year.

If you see something like F098 it is June 09, 1968.

Once you have the date code, go to the site, check the two letter code (WZ and YD) for the year of the block you have and it will give you HP ratings.

Hope that helps.