Engine Serial Number

[Farmer Dean]

Just bought a large Hyster fork lift with a V6 305 in it. Engine Serial Number is 305C 534051. Is there any way to tell what year this motor is? No plates on the forklift.

[Jeannie]

Welcome to the forum Farmer Dean.

According to Jolly's site the 305C was used in 1960 and 1961. We would love to hear the story of your forklift and see a few pictures for the club if available.

Have a great day,

-Jeannie

6066 GMC Club

[bigblockv6]

The only one that's good on identifying the year of a V6 by the serial number is Lewis Matkin. Otherwise look at some of the casting dates on the intake manifold and exhaust manifold, if original they will give you a close ball park figure of what year the engine is. The 305C was manufactured from 1960-74 not 60-61.

[Farmer Dean]

Thanks for the replies, found a 10/22/69 on the exhaust manifold; assuming they manufacture a production run of manifolds before the need them, my motor is probably a 1970? Comments?

[oldtrucksters]

According to an old AERA engine and head identifier book. 1969 is it. 305 block model e and c 515000- 536000.

[bigblockv6]

It could have very well beem an engine that was manufactured in the 1969 model year run that was left over to be used in the 1970 model year, that would explain the later dated manifolds.

[Farmer Dean]

Very good sleuth work folks, thank you for the help. Farmer Dean

[jagarra]

Originally Posted by bigblockv6

The only one that's good on identifying the year of a V6 by the serial number is Lewis Matkin. Otherwise look at some of the casting dates on the intake manifold and exhaust manifold, if original they will give you a close ball park figure of what year the engine is. The 305C was manufactured from 1960-74 not 60-61.

BigblockV6, This brings up an interesting point. If I look at a Motors Manual for our vintage of trucks I see that the letter on the engine codes changed from year to year. My 62 has a D block, previous had C and subsequent years had E models. Did GMC just use blocks from inventory willy nilly or was there some sort of sequence in the letter changes and use of the block.

I sort of always assumed that the letter changes followed the years of production, appears that is not correct.

[Ed Snyder]

If I look at a Motors Manual for our vintage of trucks I see that the letter on the engine codes changed from year to year. My 62 has a D block, previous had C and subsequent years had E models. Did GMC just use blocks from inventory willy nilly or was there some sort of sequence in the letter changes and use of the block.

I sort of always assumed that the letter changes followed the years of production, appears that is not correct.

This page from Jolly's site has a lot of info: http://6066gmcguy.com/EngineData.html but doesn't include dates available for all the different variations of the V6. But the letter designations had little to do with the years of production. The "C" version, standard in the bigger trucks, was a heavier duty engine than the versions available in the light duty trucks.

[bigblockv6]

Previous to the "D" block designation it would have been the "A" for 1960 and some 1961 models, the "D" was introduced in the 1961 model year as well and the main difference was it was a 2bbl version rather than 1bbl and ended up replacing the "A" version all together by 1962. Like Ed Snyder said The "C" version was a heavy duty version used in bigger trucks, it had the longest run of all the GMC V6 engines for 15 consecutive model years up through 1974.