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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old September 24th, 2013, 02:27 AM
62cdan 62cdan is offline
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Default How can you tell a 305 from a 351?

Hello Everyone!

Simple question for you V6 Pros...

I have a 1970 GMC 5500 Dump Truck/ Grain Truck.

It originally had a 305 in it, but the previous owner let it freeze, and cracked the block.
He told me, that, the engine that is in it now, came from a similar vintage fire truck, (w/ 22,000 miles on it). It runs fantastic, plenty of power, even in a big truck. A friend suggested that it may be a 351 instead.
Are there any identifying characteristics?
Thanks in advance.
-Mike
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  #2  
Old September 24th, 2013, 02:37 PM
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FetchMeAPepsi FetchMeAPepsi is offline
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Default Re: How can you tell a 305 from a 351?

You can look at the serial number right behind the alternator/generator on the head. The head is the thing under the valve cover. the valve cover is where the oil goes in

Here's a pic. its probably covered in grease and dirt, but its there

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Some people are like slinkys. Not worth much but funny as heck when pushed down stairs.
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Old September 25th, 2013, 04:56 AM
Foley Foley is offline
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Default Re: How can you tell a 305 from a 351?

It's fairly easy to find with Fetch's picture. You'll find a flat machined rectangular area with numbers and letters stamped into it. The first three numbers should tell you what you're looking for.
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Old September 25th, 2013, 06:05 AM
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Default Re: How can you tell a 305 from a 351?

Actually, it's BELOW where Fletch's photo points, on top of the block, in front of the head, not on the head.
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Old September 25th, 2013, 06:40 AM
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Default Re: How can you tell a 305 from a 351?

Quote:
Originally Posted by Ed Snyder View Post
Actually, it's BELOW where Fletch's photo points, on top of the block, in front of the head, not on the head.
Ed is right. It's below the head on the block but it sticks out below the head toward the front of the truck.

Sorry for the crappy advise. I barely knew what a gas cap was when I started this but as the old saying goes... ..."And now I are one"

It's right around there though. It's probably covered in yuck though so scrub a little and it'll pop right out.
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Some people are like slinkys. Not worth much but funny as heck when pushed down stairs.
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Old September 25th, 2013, 06:01 PM
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Default Re: How can you tell a 305 from a 351?

From Jolly's site
Attached Images
File Type: jpg GMC engine number location.jpg (33.7 KB, Multiple views, 11 clicks)
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Old September 25th, 2013, 07:34 PM
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Default Re: How can you tell a 305 from a 351?

Good job Funky61, and that'll sure give him what he needs, but if you have time, would you PM me about what kind of magic did you use to get that picture from Jolly's stuff, which is on this site now I think, over to where you could make it appear on this thread? Huh? Could ya?
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Old September 28th, 2013, 07:56 PM
62cdan 62cdan is offline
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Default Re: How can you tell a 305 from a 351?

Upon looking at the pad, it was clean enough to read, it is a 401.
Thanks for everyone's help.
I am not new to old trucks, just new to old V6 trucks!
-Mike
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Old September 28th, 2013, 11:17 PM
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Default Re: How can you tell a 305 from a 351?

Quote:
Originally Posted by 62cdan View Post
Upon looking at the pad, it was clean enough to read, it is a 401.
Thanks for everyone's help.
I am not new to old trucks, just new to old V6 trucks!
-Mike
And you're starting with one of the best there. nice find!

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Some people are like slinkys. Not worth much but funny as heck when pushed down stairs.
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